LX50, StarFinder Dob, & Magellan Topics

MAPUG-Astronomy Topical Archive     AstroDesigns    MAPUG-Astronomy.net



Subject: Magellan II Accuracy & Alignment Issues      Top

From: Nigel Burge <nigel.burgea_tpobox.com>

I own an LX50 8" with Magellan II and I have seen a number of posts which seem to fall into two distinct camps. Firstly, those for whom it works well and secondly, those who simply cannot seem to get it to work accurately. Since

I have now moved from the 2nd category into the 1st, I thought I would share my thoughts and experiences and hopefully this will assist others who are currently struggling with the Magellan.

1. It seems to be important to accurately level the scope. I do not understand why since the scope is polar aligned but it does make a difference. (Any ideas why?)

2. Reasonably accurate polar alignment is important. I set the setting circles to the coordinates of Polaris and then center Polaris in the FOV.

3. The most important consideration with Magellan is choosing the two alignment stars. The following does not apply if only one alignment star is used. When I first started using Magellan, the accuracy was very variable indeed. Sometimes it would be very good and sometimes quite appalling. I have found that the two alignment stars should be between 25 degrees and 75 degrees apart. I usually try for 45 degrees apart which is usually achievable. The stars should be as close to the celestial equator as possible. The first alignment star should be where you intend to first observe since accuracy will be best around the first alignment star.

At first, I was trying for as large a separation of alignment stars as I could get, but have found that if the separation approaches 80 degrees, accuracy suffers enormously. For example, Hamal and Castor are 82 degrees apart and if these are used as alignment stars, the accuracy decreases as you approach the zenith and can easily be 30 degrees out. On the other hand, if Hamal and Aldebaran are chosen which are 37 degrees apart, accuracy is very good throughout the sky. Common sense would indicate that a wide separation would be better so I wondered why this was not the case. On the assumption that the algorithm that Magellan uses is a cosine function, it would be inaccurate at a separation less than 25 degrees which is what the handbook says and would also be inaccurate approaching 90 degrees. This would appear to be the case here. If anyone knows how Magellan works out its alignment, I would be very interested to know.

One point to watch is that as long as you accurately center on ANY alignment stars, Magellan will give you an accuracy reading of about 100. This is purely the accuracy of your centering the stars and initial polar alignment: it is NOT a reflection of the accuracy of how Magellan will perform. I have had Magellan giving me 100% accuracy on centering stars with terrible actual accuracy when the alignment stars have been close to 90 degrees apart.

4. Once you have performed the two star alignment, accuracy will be very good in the region of the first alignment star chosen, to within ten degrees. Anywhere outside that region and the accuracy will fall off. However it is easy to synch on any bright star in the region in which you wish to observe to bring the accuracy back. The Magellan manual only gives a few stars and implies that this is all that there are. This is not the case. Magellan has the same star catalogue as the LX200 comprising 251 alignment stars and 100 double stars. Somebody kindly sent me a copy of the pages from the LX200 manual detailing these stars and I transcribed them into an Excel spreadsheet to show star number, position, Bayer letter and proper name. These can then be sorted by any of these, but sorting by Bayer letter is very useful.

Before a nights observation, I make a list of the objects I want to find, look up each one's brightest star neighbor and then look up the Meade star number. It is then a simple matter to synch on the bright star and then go to the object I want to find. This invariably puts the object very near the center of the FOV of a 32mm eyepiece.

I hope this helps others with Magellan so that they do not have to go through such a long learning curve as I did. At the beginning, I thought I had made a mistake buying the Magellan but I am very pleased with it now and get excellent accuracy every time. What I cannot understand is why all this is not in the manual!!

If anybody would like a copy of the Excel spreadsheet comprising the alignment stars, let me know by private Mail, and I will send it.


Subject: Magellan: Building an RS232 Cable   Top

From: Alistair Symon <asymona_tgushie.demon.co.uk>

I put a question to the group a few weeks ago on how to wire up an RS232 cable that will connect a Magellan I to a PC. Thanks to the many replies (especially from Pat Hensley) I now have this working. The reason I had to ask the question in the first place was because the pin numbering diagrams in the Meade manual were confusing. To help others who may want to build such a cable in the future I have put a page together on my website that describes (hopefully more clearly than Meade) how to build such a cable. I believe the same instructions will also work for a Magellan II. The page can be found at:

   Should open a new browser window over this page.


Subject: LX50 Dec Fix Kit-Now Available

From: <jblessina_tworldnet.att.net> Date: Jan., 1998

While this is also a commercial advertisement I hope it will be excused this once to make an announcement of an available fix for the many LX50's out there with Dec motion problems. An archive search will show that myself and others have been searching for an answer to this for some time. I promised in an earlier post that I would make it known if I could source the proper parts and put something together for all of us. It's not quite like I'm hawking red LED flashlights...

--------------If you own an LX50 and are experiencing either of these problems:

1. Slow/Fast/Slow/Fast "straining" motion in declination.


2. Grossly mismatched DEC vs. RA speeds. (Dec runs much faster than RA making small corrections difficult, especially when combined with #1!).

Then your fix is finally here! The LX50 Declination Modification kit. This kit works by "Correcting" the declination gear ratio from Meade's poorly selected 1.8:1 to a much more suitable 6.75:1. It appears Meade made a "compromise" in gear ratio selection due to physical constraints on the fork arm. This modification bypasses those physical constraints through the use of a third (idler) gear which allows greater selection of proper gear sizes. Once installed the dec motion much more closely matches the speed of the RA drive AND available torque is more than TRIPLED!

This allows more accurate guiding (manual or autoguider), easier centering, and more torque available for heavy accessories mounted to the OTA. The kit installs easily in about 5 minutes.


  1. Idler gear assembly (gear, bracket, shaft, preassembled)
  2. Resized Pinion gear
  3. Cable corrector (installs on dec cable to correct reversed rotation due to idler gear).
  4. Illustrated installation instructions and 1 Year warranty

The gears are high quality, constructed of nylon and black acetal, manufactured by the same OEM as factory Meade gears. This is a nice easy clean installation, no hack! NO HOLES TO BE DRILLED, fits under existing screws. Can be restored to original in minutes.

Introductory Price $29.95 (US) + $5.00 shipping/handling.

To order or for more information contact <jblessina_tworldnet.att.net>


Subject: LX50 Connector Pin-Out    Top

From: Joe Torelli

Here are some posts that helped me to get it to work:

Post 1:
I used the settings as listed in the Magellan II manual, -300 baud, etc. My initial setup didn't work either, until I realized that the phone jack connector pin-out was backwards from what I interpreted. The proper perspective for the cable jack pinout drawing is viewing it from the rear (cable side). Maybe that's the problem you have also. Viewing the cable from the rear the connections to a 9-pin RS232 connector are, looking at rear of cable connector (cable side), 1st is far left, 6th is far right.(Sequence: 1, 2, 3, 4, 5, 6) -

1st - no connect
2nd - DB-9 pin 5
3rd - no connect
4th - DB-9 pin 2
5th - DB-9 pin 3
6th - No connect

If your using a standard phone cable the 1st and 6th (outside) are usually not terminated. Only the center 4 are (2-5)

Post 2:
I used ECU ("Earth Centered Universe") when I had it working. I used COM1. I'm sure I used COM port settings; 300 baud, 8 data bits, Odd Parity, & 1 stop bit.

You might have a COM port conflict. You don't want to use COM 1 & COM 3 or COM 2 & COM 4 at the same time, i.e., if your mouse is on COM1, don't use COM3 for the Magellan. It would be safe to use COM2 if COM4 was configured for your modem since you probably wouldn't be using your modem and Magellan at the same time. You might want to try playing with HyperTerminal or the windows terminal program (Win3.1). The various commands are listed in the Magellan II manual.


Subject: Connecting LX50 to Computer for Software Control   Top

From: Joe Torelli

I use Sky Map Pro on my LX50-10. I must plug it into the Mag-II hand controller. Without the hand controller there is no serial port. There is a solution.
Try: <http://www.nova-astro.com/mg5.html>

This will go from the encoders to the serial port.


Subject: LX50 Dec Test Results -Chips, Motors, & Gears!   Top

From: Jordan Blessing

After receiving quite a few emails about the new Dec motor & Rev. 6.0 chip, and about the Dec fix kit I decided to do some comprehensive testing. I tested all the various parts in all possible combinations to see what works best, and what doesn't.

Below is a table showing the most interesting (bleh!) or promising combinations. I know tables often get skewed in postings, I am adding carriage returns so make your window wide and hopefully it will be straight. There are two numbers listed for each speed, the # to the left of the "/" is in Degrees Per Minute. The number to the right of the "/" is a smoothness rating. This rating is from 0-5. 0=Unusable! 1=Speed is very inconsistent to 5=Speed is very even and motion is very smooth. Here are the results:

Combination            2X         8X        16X        32X 
RA Speed as
a reference               .82         2.3         4.1          5.4 

5.X Chip
Old Motor                 3.6/1       7.2/1       8.7/4        14.8/5

5.X Chip
Old Motor
Dec Fix Kit               1.8/4       2.5/4       3.2/5        5.0/5

6.0 Chip
New Motor                 .72/1       3.2/1       5.4/2        7.6/4

6.0 Chip
Old Motor                 .36/0       3.2/0       9.0/5        13.3/5

6.0 Chip
Old Motor
Dec Fix Kit               1.0/5       2.2/5       3.8/5        5.3/5

My personal favorite is the last one. Notice how closely the speeds match the RA speeds, also notice the excellent smoothness rating across the board. I don't think it gets any better than this. Compared to the same setup with the 5.X chip you are slowing the 2X speed even more (the slower the better for guiding) and still getting a wee bit more speed at 32X (a nice acceptable slew rate for the Mag II 2 degree slews).

Notice the scores for the new motor with 6.0 chip. While the speeds are very good the smoothness ratings are pretty poor. I even reran this test to make sure it wasn't a typo when I started typing it in! It is usable but lacks the smoothness I expect of a precision instrument. The lack of smoothness is what can really frustrate guiding, one tap..no movement... another tap...out of the reticle (or off the CCD chip).

Note that the testing was done on an 8" LX50, moderately loaded, reasonably balanced, tangent arm centered, 6 new alkaline cells (all ratings would probably be somewhat improved by running from a solid 12V

source, the scope comes with AA's so I feel it SHOULD be able to operate properly with them). Degree Per Minute readings were calculated from Mag II encoder counts. You can also see that the terms 2X, 8X, 16X, 32X have little relevance to real comparisons of sidereal rate in either Dec or RA.


Subject: Fixing LX50 Dec Axis Stiffness Top

From: Gary McKenzie

Part 1--

The Problem:

In common with most, if not all LX50s (apparently), my scope had very stiff motion around the Dec axis. It made it impossible to use a finder scope or Telrad to align the scope with an object by hand - getting to within 2 degrees was a trial, and the scope had to be slewed using the drives to center an object. One handed motion was not possible, I had to grab the scope with both hands to move it even close to where I wanted to go. This became a real problem recently when I fitted an NGCMAX DSC. I could move the scope beautifully in RA guide mode till the display read 0#0, but in Dec I still had to electrically slew the last couple of degrees in dec. The problem was a great deal of "stiction" i.e. it took a lot more force to start the scope moving than to keep it moving. This resulted in jerky movement and overshoot. Also correction in Dec at 2x speed seemed jerky - like the scope was straining to move, then broke "stiction and moved.

The Result:

The Dec axis is "silky smooth", has no "stiction", and with the clutch off will drop to heaviest point down from any position with no push to start it. I now, no longer have to slew electrically to position objects according to the DSCs. In addition, I "orthogonalized" the mount and accurately set the Dec circles, while it was apart. This has resulted in the following:

- after rough polar aligning and
- two star aligning on Vega and Achernar using a reticle eyepiece I receive a warp value of 0, and can GoTo an object ANYWHERE in the sky and find it in the central quarter of a 32mm Plossl eyepiece field of view.

Subjectively, it just feels "nice".

What You Will Need:

  1. Download from Ed Stewart's MAPUG Topical Archive, the procedure for orthogonalizing the Dec axis.
  2. hex keys for:
    • the fork bolts
    • Dec motor mounting bolts
    • Dec gear
    • tangent arm adjuster (at top of fork)
    • screws that hold tube adapters that permit mounting of scope to fork 3. LARGE flat bladed screwdriver
  3. wheel bearing grease or similar thick grease.
  4. couple of pillows to support and protect the scope as it is lying down.
  5. tissues or clean rag.
  6. pair of long nose pliers (not everybody will need these)
  7. GOOD, i.e. accurate, spirit level (for setting the Dec axis circle to "0") 9. screws to fit the adjusting points for tube adapters on side of scope (see article on orthogonalizing mount)

Part 2--

Step 1.

Remove the setting circles from both sides. Note that on the side with the encoder socket, that there is an easily lost small black washer that fits between the setting circle and the Dec shaft. On this same side there is a space roughly an inch in diameter and an inch long that looks like it is the Dec shaft, give this a tap and it will fall off- it adheres only by some dried grease if at all. This will expose the actual Dec shaft.

Step 2.

Lay the scope on its side on the pillows - I worked on a carpeted floor on the principle that if anything fell over, it would have less distance to fall. The side with the Dec motor should be facing upwards. Loosen the set screw on the small Dec gear (the one attached to the motor). Remove the 2 hex screws that hold the Dec motor to the fork - note that the one closest to you may not be fully removable yet as it may hit the gear. Now, holding the motor in one hand, take your large flat bladed screwdriver and insert the blade between the motor and the fork. Twist the blade such that the motor is forced away from the fork perpendicularly, this will have the effect of bringing the small plastic gear hard up against the other side of the fork. With gentle pressure keep twisting the screwdriver and the plastic gear will pop of the motor shaft. This may require quite some force as the gear appears to have a spot of glue added to it as well as having the previously loosened set screw. You can now remove the hex screw that the gear interfered with. Put the motor aside.

Step 3

Loosen and withdraw the 4 screws that hold the fork to the central axis. These tend to make an alarming "CRACK" noise when first loosened as they are VERY tight.

Step 4

Place one hand under the top of the fork arm such that you are supporting the fork and the tangent arm and one hand under the bottom of the fork and lift away - this was sticky on my mount as the nylon bearing at the top of the fork gripped quite tightly. If this nylon bearing is stuck in the fork arm push it out. The Dec bearing assembly consists of the following from the fork towards the tube:
  • -hole in fork for nylon bearing
  • -nylon bearing
  • around Dec shaft on tube:
  • -washer
  • -flat roller bearing
  • -washer
examine the fork, mine had several bits of casting that rubbed against my tangent arm stopping it from seating correctly, if yours is the same, snap them off with the long nose pliers (these casting leftovers are unmistakable so don't worry. My bearings had little to NO lubrication, the nylon had a smear, the rollers had none!!!
Coat every part of the bearing assembly with copious amounts of grease, don't be worried about any excess. Coat both sides of the washers, put a thick coating on the roller bearings, coat both sides of the nylon insert, coat the hole in the fork, COAT EVERYTHING. When you put it back together grease should ooze out of the parts. Clean any excess with tissues/rag. Now loosen the adjusting screw on the tangent arm - a hex screw at the top of the assembly.
To reassemble, insert the nylon bearing into the fork arm, - watch the oozing grease. Then maneuver the fork arm over the Dec shaft and firstly, let the tangent arm seat itself, then slide the fork over the Dec shaft more oozing. Seat everything properly. Now insert the four bolts into the fork arm and base and screw them up loosely (you will have to adjust them later).

Step 5.

Do the other fork arm in the same way - you don't have to worry about the tangent arm though. The bearing is exactly the same construction here.

Step 6.

Follow the procedure for orthogonalizing your Dec axis. Then adjust the tangent arm to suit. Refit the Dec motor.

Step 7.

Set the Dec setting circle as follows:
  • - Sit the scope on its drive base with the control panel facing you.
  • - Using a GOOD spirit level, level the base in a left / right direction i.e., place the spirit level across the top of the control pane (may have to rotate the scope about the RA axis to do so)
  • - rotate the scope such that the tube assembly is also in a left to right direction ( a fork is directly in front of you in the center of the control panel)
  • - make the tube horizontal using the spirit level, set Dec circle to zero, spin around DEC axis 180 and is level, check circle still reads zero, adjust as necessary.
  • -tighten up the setting circle with the scale reading 0 .

Your Dec axis should now be as smooth as silk, and it should point very well as it is now assembled better than it left the factory. If anything is not clear let me know, and hope it improves your viewing pleasure as much as it has mine. (Mr. No responsibility taken should you screw-up your scope!!!!)


Subject: LX50 Dec Wobble Fix   Top

From: Nigel Burge <nigel.burgea_tpobox.com> Date: Feb., 1999

The original poster found that the wobble in the Dec train which shows up clearly in a side to side motion of the large Dec gear and in a fast/slow speed on 2X (even with the excellent Jordan Blessing Dec Fix Kit) was not due to a bent threaded rod etc. but was solely due to the fact that the carrier for the large Dec gear is fixed to the end of the threaded rod with the usual hex screw and that this causes the carrier to be fixed eccentricity on the rod.

Since the gear carrier is not a particularly snug fit on the threaded rod, the original poster suggested shimming between the rod and the inside of the gear carrier with tin foil to remove the play and cure the wobble.

I got round to trying this out on Friday and ....... it worked brilliantly. It was a long job to get the tinfoil shim in exactly the right place since everything moved as soon as I tightened down the gear carrier hex screw, but after a considerable amount of trial and error, I finally got everything in a position where the wobble of the large Dec gear against the smaller pinion gear was virtually eliminated.

This in turn has resulted in the 2X Dec speed being completely smooth with no variations in speed at all.

I would like to thank the original poster (I wish I knew his name) for this excellent idea which removes a most annoying problem which seems to affect a considerable number of LX50s. What is even better is that it is so simple to cure.


Subject: LX50 Dedicated Web Sites  Top

From: Bryan Tobias <btobiasa_tsbcglobal.net>

I have a number of upgrades and fixes for the LX50. They are listed on my website at:
Note: should open a new browser window over this one.

Also see Bill VanOrden's LX50 site <billa_tbeevo.com> <http://www.beevo.com/Telescopes.htm>


Subject: Reinstalling LX50 RA Fine Adjustment Knob  Top

From: Joshua Kent

>>I thought my RA fine adjustment knob felt loose so I unscrewed the set screw and removed the knob. Now I can't get it back on! There is a thin vertical pin that the knob goes down over and the set screw tightens against. The only problem is that the pin slides up and down and I can't hold the pin up while placing the knob over it at the same time.
I assume that the other end of this pin has a gear which meshes with the RA train somehow. The pin also has a small cam around it, I guess for feel while turning the knob. I've taken off the bottom base plate and the top cover plate (LX50) to see if there is access to the pin assembly. No sign of the pin assembly. Any help would be appreciated.<<

I've had this same exact problem. Well, almost. My gear rod fell out completely as I was turning the RA the first day I got the telescope. I spent about 8 hours trying to get the thing to work. I can tell you know that you're better off not worrying about it. Simply because you'll never really use the manual RA adjuster. But, I know it's heart breaking to experience it, so here's what I did to fix it.

First, you'll notice that the cam holds the gear rod (the pin) off center. Well, you have to pull the gear rod up as far as it can go. Then, rotate the cam so the gear rod makes contact with the RA spur gear (so that the thinnest part of the cam faces away from you). This is very difficult to accomplish. You'll have to unlock the RA clutch and rotate the fork arms so the cam turns the gear rod easily so it meshes with the spur gear. Remember to hold the gear rod with your fingers. It has a tendency to slip down into the gear housing.

When you find that the gear rod meshes nicely with the RA spur gear, then tighten the cam down using the little hex nut at the base. Then, making sure the gear rod is stable, rotate the fork arms a couple of times and see if the gear slips down. If you see it starting to slip down, then grab it and pull it back up. You want to make sure the gears mesh nicely (since you don't want them to eat each other as you rotate the fork). IF THE FORK IS HARD TO ROTATE: then you've meshed them too tight.

When you're satisfied that the fork rotates easily, the gear rod is meshed nicely, and the cam holding the gear rod doesn't move around or slip out of position, then attach (careful not to push the rod down) the RA knob to the gear rod. Then tighten the knob on the gear rod using the hex nut in the knob. This will stop the rod from dropping into the gear housing. By the time I got this to work, I'd eaten up the rod, the hex nuts and the cam. I called Mike at Meade and he sent me new ones to replace the one's I mangled.

Like I said before, it's very disheartening to have this happen, but this knob is really not necessary. Just put a cap in the hole and call it a day. You'll use the RA knob maybe 2 or three times and then never again. The hand paddle is easier to make the small adjustments.


Subject: Fix for LX50 RA Adj. Knob Looseness  Top

From: Patrick Lanclos <SkySgta_taol.com> Date: Aug., 1998

Just read the tip in the MAPUG Topical Archive concerning LX50 RA knob looseness and the problems other owners have faced when trying to reinstall the knob. Please let me add my two cents worth to this topic.

I too had this problem with my LX50 and like most everyone else, I took the knob off to see if I could fix it. Of course, I had a heck of a time getting it back on because of slippage of the shaft. Everytime I tried to slide the knob down over the top of the shaft, the shaft would slip back down into the scope housing. This slippage didn't leave enough of the shaft protruding for the Allen screw to grab hold of.

What I did to get the knob back on, was to go to my local Home Depot and purchase a 1/8" C-ring (I believe 1/8" was the size, anyway, it was the smallest C-ring they had). I then took a pair of needle-nosed pliers and pulled the shaft up out of the housing and held it there while I clipped the C-ring onto the base of the shaft, above and flush with the top of the offset cam that the shaft protrudes from. This solved the problem nicely! The C-ring keeps the shaft from slipping back into the cam. I can pull the knob off as many times as I want to, with no worries.

The only tools I needed were a pair of needle-nosed pliers and a "pocketsize" flathead screwdriver. To install the C-ring, I laid it on top of the cam with the open end up against the shaft. I then used the flat nose of the screwdriver to force the ring onto the shaft, making sure the ring stayed flush with the cam. This will require quite a bit of pressure, so be careful not to stab yourself with the screwdriver.

When doing this procedure, be sure you are in a small sized room with very light colored carpeting or floors. The reason is, the C-ring opening is quite smaller than the diameter of the shaft, and the shaft has no groove on it for the ring to slip onto. Needless to say, to get the ring around the shaft requires some "elbow grease", but it can be done. The small room and light colored flooring will enable you to find the C-ring again if it should go flying across the room (and it inevitably will). The C-ring is only about the diameter of a #2 pencil eraser and will easily get lost if you are not careful. It took me 3 tries and 45 minutes to get the C-ring on the shaft (about 40 minutes of the time was spent looking for the C-ring after the first two tries). Total cost of the fix was $1.50 (the cost of the C-ring).


Subject: Magellan II Digital Setting Circles for LX50  Top

From: David Bonnell

Brian Straight wrote:
> Does anyone have any suggestions re DSCs for an LX50. I'm
> currently considering the Sky Vector at $439. is it worth the
> price difference re the Sky Vector I or II? Are there better
> bargains out there?

I agree with Scott Strawn - I too have the Magellan II for my LX50, and, while I am not as effusive as Scott about it, it is physically well engineered, and integrates with the scope. It does have the advantage of integrating the current handbox functions into one pendant, and I find the control features better human engineered. In any case, you may need Meade support to get the electronics and the motor upgraded to work properly if you try to control the scope as well as simply help you position it. That will probably be easier if you intend to integrate Magellan. However, Lumicon products are extremely well thought out, and tend to represent some of the best hardware solutions available. You won't be making a mistake to go that route, but it won't be as "integrated" a solution.

As far as the Magellan II - getting it to work with your scope may be an eye-opening experience. There should be some commentary in the archives on this subject, as it has been a recurring issue. But, I now feel that I can fairly reliably calibrate Magellan in reasonable time, and that, with liberal use of the Sync function (which may not be available on the Sky Vector (Meade's claims suggest not)), it is possible to roam the sky and get reasonable pointing results. Even the LX200 users need to sync after major moves in many cases.

However, at best, I find that Magellan will get me within a 1 deg FOV on larger swings, once it starts to find things. The polar + two-star alignment offered is a waste of time. Best is a good polar alignment, one alignment star in your first area of observation (simply press the MODE button when asked for the second star). Then, find something within approx. 10-20 deg, and sync. It shouldn't be too close, or too far away. This time of the year, I usually align on Vega, then sync on M57. What ever you do, don't try to sync on two objects that are really close, or sync twice on the same object. Magellan can lose it entirely! If you need more info, check out Nigel Puttick's comments. He really has the handle on Magellan.

An alternative - JMI has a similar system, and I have heard rave responses from owners. I personally have no experience, but while I was still struggling with Magellan, I did think about switching! But, I was never convinced that the problem was Magellan, as opposed to my technique (or maybe a scope mount problem). Magellan II still requires a polar-aligned equatorial mounting - it does not work as an Alt-Az tool. Partly, this is because of the tangent arm Dec drive, which is not suitable for two-axis, all-sky, powered pointing. You will have to do most of your pointing the old-fashioned way, unclutching the RA and DEC locks, and swinging manually. Magellan II is designed to work successfully that way.

The main thing is, DSCs are no substitute for knowing your equipment, the basic techniques for setting up, and the sky - at least for the LX50, you will have to regularly find (or identify) objects, and resync on each new find to retain enough accuracy (as opposed to precision - Magellan precision is quite adequate for most uses) to reliably put faint fuzzies in the field. A good wide field EP is also a big asset! Finally, if you are into Astronomical League clubs, be aware that, at present, using DSCs to find objects doesn't count.

Speaking of Magellan II, it is well past time for new, better firmware - does anyone know if or where to obtain Magellan II updates - or why Meade is not providing that support? I am convinced that Magellan is using a rather unrefined alignment algorithm, and that Meade should be well aware that more robust alignment and sync strategies are needed. Otherwise, tools like Sky Vector... will become the clear preferred alternative, despite the integration advantage of Magellan.

By the way - DON'T plan on running Magellan from the internal LX200 battery pack. It will do it, but rapidly drains the batteries, and motor response gets sluggish fast. Plan on adding a 12V external battery. If you can find a small (tractor-sized) marine deep-discharge battery, or adapt a gel cell of the kind now common in UPS's, you will be much happier - I actually have a medium-sized standard Marine battery (it came with a carry strap) that cost ~$31 new. Radio Shack sells several styles of cigarette-lighter receptacles. Nothing fancy is needed! You get juice to run the scope "forever," extra for dew heaters, atlas-lighting..., and no more having the scope die in the middle of a session (which WILL happen if you try to run Magellan from the internal pack). With Magellan and the LX50, simply plug in the 12v Battery using the supplied DC cable, and you're in business - no other batteries needed. Making this work with a 3rd party DSC may be more complex - I would hate to travel an hour or two to a dark site, get set up and aligned, observe for a few hours, and have the DSC die well before I was ready to quit because it's little 9v battery ran out of juice. It's bad enough when my Telrad goes dead during a session!


Subject: Magellan I & II Alignment Stars  Top

From: Alistair Symon <asymona_tgushie.demon.co.uk> Date: Sept., 1998

The accuracy of the Magellan I and II is heavily dependent on the stars you
use for alignment. I have a in-depth discussion on my website on the
various ways you can obtain good accuracy. The URL is:
Note: should open new browser page over this one.


Subject: LX50 RA Drive Solution    Top

From: Gary McKenzie

I have diagnosed the problem I developed with my LX50 RA drive last night.
I am posting this for others reference.

My original post was:
my 8" LX50 has developed a problem with its drive tonight.
It is OK at normal sidereal rate, and OK at 32x , 16x ; however 8x does not work when slewing to the east (west is OK). In addition 2x in both directions is intermittent -- works sometimes, not others. Any ideas??

After disassembling the drive and running the motor unloaded I discovered that it was functioning correctly. All speeds worked in all directions, hence the problem was not with wires, controllers etc. The problem was with the mounting of the motor/worm gear assembly. The motor/gear is mounted via 2 screws to a piece of L-shaped aluminum. One of these screws is a pivot that allows adjustment of the worms contact with the RA gear.. The other controls any tendency of the motor/ gear to twist away from this L-shaped piece. On mine the screws had worked loose from the effect of torque twist of the motor - there is a surprising amount of this, I was unable to stop the twist with my fingers -- repeated twisting had loosened the screws so much that they had both stripped out their threads as well!! This allowed excessive torque twist of the assembly which caused the worm to rise onto the RA gear and stall (hence the working in one direction where the torque unloaded the worm and gear).

At 32x and 16x the motor was sufficiently powerful to still run, but at 8x and 2x it simply stalled. As the screw holes were stripped, the l shaped aluminum needs replacing. As Meade is along way from Australia, I am fortunate enough to have a friend with a machine shop who is going to make a new part for me - this time out of stainless steel. I doubt the problem will happen to me again.


Subject: LX50 Drive Upgrade  Top

From: Gary Mckenzie

Just a note to advise that Meade appears to have introduced a new drive for LX50s. The main change is that the worm gear is now brass instead of stainless steel. In addition the motor now has a small amount of epoxy glue attaching it to the worm mount as well as screws. This stops the rocking of the motor that happened in earlier units when changing direction. The electronics are 6.1. As before placing a jumper on jp4 lets the scope startup in southern hemisphere mode (important for me). The Dec drive now also works better (6.1????) My scope now has approx. +/- 15 arc secs of very smooth periodic error (previously it was more than +/- 30 arc secs.) The image will stay on the cookbook 245 chip at f50 in 1/4 frame mode for the entire cycle of the worm!!!

- I did some Mars imaging last night. Previously I would have sometimes lost the planet in full frame mode!! I have a 16 1/3 geared Dec drive with a Blessing fix kit, and the Dec works fine with this combination for autoguiding. This is a VERY well worthwhile upgrade.


Subject: LX50: Power Cord/Supply   Top

From: Richard Clemens

I use a 12 volt Gel Cell to power my LX50 as the internal AA's do not seem to have enough juice for more than an evening. Last night I broke the connector for the LX50 end of the supply and went looking for a new plug. The scope requires a 5.5/2.5 mm OD/ID Coaxial DC Power Plug but the 274-1573A connector at Radio Shack does not have any strain relief and is the one that broke. After shopping the store, I found part 270-029 which is a coiled cord for a Radar Detector with nice right angle strain relief plug. I cut off the cigarette lighter end and replaced it with my own connector and it is a nice addition. BTW anyone else have problems with the 6 AA's furnishing enough power?


Starfinder Dob & Magellan Issues 



Subject: Meade Starfinder 16" Dob--Upgrading   Top

From: Michael Hart with additional comments from Ed Stewart <stargazera_tskymtn.com>


I have experience with Dobs of this class and larger. As I recall, the 16" rocker box is made of high density particle board with an overlaid and cured white coating on the panels. The altitude trunnions are solid cast nylon (the round discs attached to the scope tube). The altitude and azimuth bearings look like Teflon but are probably high density polyethylene. This is important which I'll explain later.


The action of a Dob determines how well you can hand track and the maximum power you can use practically use. A well set up Dob hand tracks so smoothly, you track unconsciously and effortlessly.

Mass produced and even semi-custom Dobs are set up for anticipated eyepieces and accessories. Generally the mass produced Dob will have tighter action to allow them to work for a larger range of customer types and accessories. You can adjust the action to suit your eyepieces and accessories.

Tweaking a factory Dob for silky smooth action is worth the effort. You have already tried some of the recommended tips such as wax which as you found out, are not a permanent fix. The reason is the high density polyethylene pads scrape the wax away. You can add Teflon pads used by the Obsessions to replace your harder, but less slippery pads, but Teflon is quite soft and does wear down. The smaller the pad, the lighter the action, but faster wear. In addition, you will still get some stiction when the pad conforms to the surfacein about a minute or less. You probably know the symptoms- when you stop moving the scope in azimuth a minute or so, it takes much bigger push to get it going again. We'll talk about a MUCH better fix for the azimuth a little later.


Replace the polyethylene pads under the altitude trunnions with Teflon, move the pads down to decrease resistance, up to increase resistance. Remove the rocker nut and the rocker box from the ground board. Replace the pads with Teflon. Smaller decreases resistance, larger increases resistance.

THE ULTIMATE FIX- Start By Balancing The Optical Tube

Now is the time to balance the tube with your heaviest eyepiece. This is important as we are going to lighten the action of the altitude. The best way to balance the tube is to move the altitude trunnions.

This is somewhat difficult and the mirror box may end up too low in the rocker box. Another way is to add weight to the inside or outside mirror box to tweak balance. Their are optimal places for the weight too, but it is rather difficult to explain. Essentially, you want enough weight opposite and across the eyepiece and finder. Then add additional weight as needed behind the center of the mirror or evenly around the mirror box. This method effectively counters the off axis weight of the focuser, eyepiece and finder.

The result is the scope that has the same balance and feel in any position. If this seems difficult to understand, adding weight to the rocker box is fine, you just won't be able to have the altitude bearings set lower for as light an action as the scope won't hold it's position in some locations.


Now, replace the high density polyethylene pads under the nylon altitude trunnions with Teflon. The lower the pads, the lighter the action in altitude. Check balance again and secure the pads with small wood screws, I recall using a #2 brass wood screw. Drill holes as the high density particle board won't take screws well without drilling. Countersink the pads so the screws don't touch the trunnions, but use only one screw at this time because we're not done. Altitude bearing stiction needs to be corrected and the altitude bearings surfaced to match the nylon altitude trunnions on the tube.

Use some 1" wide 100 grit sandpaper around the trunnions with the abrasive facing the Teflon pads. Move the scope up and down to sand the Teflon to match the trunnion curve. Do this to both sides. Now remove the tube and place it on a couple of chairs. Use 80 grit sandpaper to roughen the nylon trunnions. Don't worry about the sandpaper being too coarse as coarse sandpaper is needed to cut into the nylon. Spend 30-45 minutes sanding each side.

The large Dobs often use ebony star Formica with bumps to minimize stiction. Your modified trunnions are better. Teflon from the pads is eroded by the trunnions, filling the rough surface with Teflon making a Teflon to powdered Teflon surface that resists stiction remarkably.


Stiffening the rocker box increases the feel of the scope and improves hand tracking at high power. The tall sideboards of the Meade Dob are stiffened by adding outside boards. It is tempting to use a 2 X 4, but the added thickness does not improve stiffness much, but adds dead weight.

Use 4" by 3/4" hardwood such as oak and cut the same length as the side boards are tall. Place the board on the outside of the rocker box and secure with wood screws through the inside and underside of the rocker box. Use a lot of screws as wood glue won't readily adhere to the sideboard surface. Locate the boards a couple of inches or so toward the trunnions. Cut another piece for the rear opening of the rocker with an arc that just clears the mirror box. Secure with screws as before.


The big Dobs from high end companies such as Obsession use Teflon on the ground board that the rocker box pivots above. We will NOT use Teflon here. First, remove the pivot bolt nut inside the rocker box and mark the bearing pads, then remove them. Go to a bearing supply house or well stocked hardware store and buy three small precision bearings with shields. The size should be 1/4" ID and the smallest OD available within reason. Pick up (3) 2-1/2" long 1/4" bolts of grade 5 or higher and six 1/4" washers of a smaller diameter than the bearings. In addition, you'll need a 1/2 sheet of SMOOTH Formica, the smoother the better. Look for split or damaged sheets which you can buy cheaply. Include 50 1/4" #4 flat head sheet metal screws.

Cut off the threads and the bolt head. Now, center the pin over the marks you made on the ground board around the pads you removed. Use a router or Dremel to cut a slot pointing to the pivot bolt. Cut a deeper and wider slot for the bearings. The pin slots should be deep enough to allow the bearings to hold the rocker box 1/8" above the ground board. Now, use a saber saw and blade for laminates (a fine blade) and cut the smooth Formica the same diameter as the rocker box. Drill the center for the pivot bolt and smaller holes around the outside circumference for the #4 flat head screws. Install the Formica on the underside of the rocker box and secure with the #4 screws. The idea is the bearings will roll on the smooth Formica under the rocker box.


At the next star party invite a someone who owns one of the high end Obsessions or other high end Dob to view something through your modified Meade Dob. Watch his jaws fall as he experiences fantastic feather light action from your Meade Dob.

> Todd--if you decide to go as far as Michael Hart describes, then you might as
> well go all the way to a motorized tracking system that requires mostly the
> same modifications--the DobDriver II. For a complete description of its
> installation and suggested modifications of that installation, go to the link
> AstroDesigns and select the "Installing the DobDriver II" button. I devised some dirt
> protection to the ball bearing's track that you might find of interest. I
> found that just one sand grain could bring the az system to a screeeeching halt--Ed Stewart

I have also installed a Dob Driver II and you are indeed correct about the grit problem, hence my recommendation the bearings be on the ground board in place of the old bearings with Formica under the ground board. One bearing should be OK for the 16", I used doubled bearings. I didn't explain, but the smooth Formica is needed because the coating in the Meade ground board won't support the pressure in a small area. In addition, with the Dob Driver II, the bearings must be under the rocker box and the Meade 16" ground board will probably have to be scrapped and replaced with marine type plywood such as Baltic Birch. This is because the high density particle board ground board will not support the weight of the scope that sometimes SPANS the feet with the Dob Driver II retrofit. Here, the groundboard supports weight. The originally bearing pads and my proposed bearings reside directly on top of the feet. Here, no weight must be supported by the groundboard. I would say that having average to advanced mechanical skills will improve the finished Dob Driver II installation, an important consideration. Mine was improved with a quick release lever for the drive motor, replacing the knob.

I found smooth Formica worked better for the Dob Driver II as well by slightly offsetting the knurled drive wheel so the bearings were in smooth tracks, while the drive wheel was it it's own track.

> In addition or separate from these modifications, the best thing I ever added
> to my Dob was digital setting circles (DSC)--they really work fantastic! I
> just about lost interest in the hobby because of the frustration in trying to
> locate objects past the easy ones. Now I can easily find the next object in a
> minute--look up next object number from my list, punch in number, move scope
> to indicated position, and observe--almost as easy as a LX200! I use
> Lumicon's SkyVector, which is the same box that Orion, Celestron and JMI use.
> As to Meade's Magellan unit, there's been various praise and complaint here on
> the list so suggest you ask for comment if you consider it.--Ed Stewart

I added the Lumicon SkyVector as well. For the 16" Meade, order a Coulter kit which includes a brass pivot pin if Lumicon lacks a dedicated kit for the Meade. Maximum pointing accuracy is 6 arc minutes limited by the high res encoders. Careful installation and adjusting of trunnions and a vertical stop must be done to achieve this. My personal Dob has an on board battery with LED voltmeter and charger for electronics and dew heaters. An electric focuser is controlled from the Dob Driver control box that plugs into a jack with all wires inside the scope and rocker box. A heated Telrad, heated 9 X 60 finder, heated secondary and cooling fan rounds out the setup. In addition the Lumicon box is affixed near the eyepiece.


Subject: Upgrading Starfinder Dobs--Update     Top

From: Bruce Rubenstein

I followed your recipe for upgrading a Starfinder Dob at the Mapug Topical Archive to upgrade my Meade 16. In general the process described there worked exceptionally well, and I am very pleased. Thank you so much for providing this information.

Allow me to add a couple of my own comments:

Rather than using a jigsaw or sabersaw to carve the formica, I used a plunge router with a laminate trimming bit. The bit I used cost $12 and produced a chamfered edge. Its ball bearing guide contacted the ground board all around without cutting it. The router carved a channel right through the formica, obviating the need to cut the formica accurately to size before trimming.

For screwing down the formica, I used low profile pan-head screws. Countersinking the thin formica seemed too difficult, so I avoided it. A problem arose once I assembled the completed mount, however, in that the tops of the screws chafed against the ground board. As it turned out, clearance wasn't the problem. Rather, the chafing resulted from the ground board warping under the weight of the scope. This problem was quickly solved by placing three "feet" on the bottom of the ground board as close as possible to each of the three bearing assemblies. This way, the weight of the scope and rocker box transmitted straight down through the bearings to the feet and straight into the ground. The feet must be placed within an inch or so of the bearings to avoid warpage (I think. I didn't actually try moving them).

Once the chafing problem was solved, the scope could spin freely about its new ball bearing base. In fact, it spun too freely. One small shove sent the scope into a near 360. Also, small adjustments produced subtle but annoying backlash, possibly caused by deformations of the formica at the bearing contacts. Both of these problems were solved by adding small squares of Teflon between the ground board and the rocker box. I used three squares, each about 1/8" high and 1/2" square, along the outer circumference of the ground board. One Teflon pad was placed mid-way between each pair of bearings. When I tried to use fewer than 3 Teflon pads total, the ground board deformed again, and the annoying chafing returned.


Subject:16" Starfinder Equatorial Mods --part 1 of 2   Top

From: Jeff MacQuarrie <jamacqa_terols.com> Date: Sept 2001

I have successfully autoguided the 16" Starfinder using a Cookbook CB245. The book and website contains a fairly simple circuit that you can build that will allow the camera to autoguide. The only modification I had to make to the given circuit was to duplicate the functionality of the hand controller for my dual axis corrector.

See the following on the Cookbook homepage:

For those interested in Starfinder mods, there is a Yahoo group that several of us started last year that now has over 140 members devoted to this scope. This group is devoted to discussions related to the Meade 16" f/4.5 Starfinder Equatorial, 16" Starfinder Dobsonian and the Meade DS-16. Discuss upgrade modifications, imaging techniques and other topics related to this scope.


You can see both film and Cookbook CCD images that I've obtained with the Starfinder 16 at:


Subject:16" Starfinder Equatorial Mods --part 2 of 2    Top

From: Jeff Gibbons <Jgibleulera_taol.com> Date: Oct 2001

I am writing to let others know about some modifications I made to my 8" Starfinder Equatorial mount. I first purchased Rotating Rings. They allow me to view conveniently but they are relatively heavy. I added 20 pounds of extra weight to the shaft and eventually purchased the weight used on the 10" Meade Starfinder. The weight is much more convenient than gym weights and I have to admit well worth the $100 or so for the item. As I added more weight I found that the scope did not track well. The motor took a few seconds to get itself up to speed and was straining. Balance became crucial. I took the scope apart and found that the nylon bushings were deteriorated, especially at the top of the RA shaft. I saw an article in ST which featured some innovative optics on a SF mount. The bearings in the mount caught my eye. I tried to find someone who did this work, but I could only find people who would "give it a try."

Eventually a chance contact put me in touch with a fellow who owns a firm which makes laser range finders for the military and who used to make radio telescopes! He certainly understood what I needed. We agreed that new bushings would work so he made replacements from oil impregnated bronze. I added a thrust bearing at the top of the RA shaft where it joins the Dec shaft.. A 1" id thrust bearing is hard to find so I settled on a metric bearing and a spacer. This bears the downforce of the mount in the axis along the RA shaft. The bronze bushing bears the weight pushing down at 90 degrees from that.

With the clutch off, the thing spins like a propeller. It is smooth with very low friction and an incredible improvement over the deteriorating nylon bushings. The motor jumps up to its proper speed and it tracks smoothly and accurately.

As an aside to all this I changed most of the screws, nuts and bolts from those used originally to ones with real Allen heads. I recommend this in any case. Just be careful in tightening. When you have a real Allen head you can overtighten and strip the threads. I also replaced all the washers with stainless and used two where possible. The original hardware will bend over time. If you adjust your clutch frequently get washers for the clutch adjusting screws, there are only lock washers there and they chew up the clutch plate if there is no protecting washer.

All of this was a prelude to getting a Magellan II. I felt that I really didn't to spend the money that unless the mount was excellent. The improvements have maximized the mount so I will buy the M.II shortly.

I have also purchased the JMI DX3 with Motofocus which is outstanding. I also purchased the JMI Wheelie Bars so I could roll the mount across the floor of my van. I just attached the JMI EZ Align which is excellent as well. It has an illuminated reticle which is the best I've seen. I've had the mirror checked for its configuration and the tests confirm the viewing impression, it is fine. I had the primary recoated at QSP with Enhanced II coating and had the secondary coated with Endurobright. The tube is flocked and a fan is mounted at the rear. The fan blows out and pulls air in through holes in the tube just above the primary. The fan is mounted in a Lumicon Tube Cover (with the center cut out) which a large rubber piece. The rubber provides insulation from vibration and seals the tube so that the air flows as intended.

Next steps will be a longer tube to minimize the secondary along with a Protostar spider . I am leaning towards a Sonotube because I like to tell my wife that it's only a "cardboard tube telescope".

These scopes have been around for 30 years so I'm sure that these changes are nothing new. I welcome ideas and corrections from the other owners of these scopes. I'll let you know how the Magellan II works out.



Subject: StarFinder Polar Align     Top

From: Mike Stute <mstutea_tcompucom.com>

If you get those bolts too tight then the clutch doesn't work, but it will still track. With all the StarFinders, after you move the mount by hand, it can up to a minute before the drive starts tracking again. I don't know why because I've never fully investigated it, but I do know there is a lag time in most mounts before the nylon clutch grips again.

Two things are extremely important: balance and alignment. The DC motors are fairly weak, and a SF 10" fully loaded with camera or CCD, motorized focuser, and 50mm guide scope can give the motor fits. In this case, loosen all the bolts on the clutch plate, carefully balance the scope and mark the position of everything so you can get there again with minimal fuss (I use red marks for astrophoto work and black for observational). You can just leave the mirror in the astrophoto position.

Rotate the scope so the shaft is horizontal, and move the counter-weight in and out until you get it perfectly balanced so it stays in any position even with the bolts completely loosened.

Rotate the scope so the scope is completely horizontal and slide the scope back and forth in the straps until you get rotational balance and it will stay in any position regarding rotation.

Then rotate it all over the place. If properly balanced it should stay put. Once you achieve that, tighten the clutch bolts so the drive will engage, and mark all your positions.

This is tough because switching from a 12mm Plossl to a 20mm Nagler, and the difference in weight is enough to cause an imbalance. Hopefully, it won't be too much.

Then as for alignment, make sure your a perfectly level and the latitude adjustment is right on. After that, standard 3-star alignment should get you going.


Subject: Magellen II ROM Question     Top

From: Tom <TheRonea_taol.com> Date: Dec., 1997

According to Mike Liegh at Meade, the LX50 comes with two motor chip sets. An RA motor assembly stamped 500K should have a thinner (~1/4" thick) chip labeled version 3.1. A motor assembly stamped 1K should have a thicker (~1/2" thick) chip labled version 5.3. I have the 500K stamped motor assembly with the ver 3.1 chip and have not noticed any problems. Mike said that some had problems due to the chips and motor assemblies being mismatched.

The correct chip would have a sticker on it that read: 35-4000-12 R 5.3. A scope with a 500K stamped motor assembly should have a chip labled 35-4000-11 R3.1.


Subject: StarFinder Laser Collimation Setup     Top

From: Mike Stute <mstutea_tcompucom.com> Date: Feb., 1998

The following procedure is used to setup a StarFinder (Dob or EQ) to use a laser collimator (actually any Newt.). You first have to do the mechanical setup and prepare the optics. Then learn the procedure for continued collimating.

1) You're dealing with your expensive optics here, remove all rings, necklaces, watches, and other jewelry.

2) Lay the OTA (Optical Tube Assembly) down on the a table so you can see the backside of the primary mirror mount. The mount has three feet that contact the SonoTube. Meade usually marks one of these feet with a small red paper dot. If you don't see this dot, then pick a mirror mount foot yourself an mark it with something that you can easily see later like a dab of red paint (you want something permanent). Mark the side of the tube where the same foot contacts the tube so you can see the dot with the mirror in place. Once again, Meade usually marks this with a red or orange paper dot. Whenever you put the mirror back in, make sure you align the two red dots or whatever marks you've chosen.

3) Remove the primary mirror by removing the three bolts in the OTA at the primary end of the OTA. These bolts screw directly into the mirror holder assembly so there are no nuts on the backside. The primary lifts out the back. Set it mirror side up and observe every precaution.

4) Remove the secondary mirror. To do this, set the OTA on the ground with the secondary at the top. The secondary mirror is mounted on a threaded rod. The rod is mounted through a hole at the intersection of the spider vanes and has two nuts on it. One nut is on the mirror side, the other is what actually holds the secondary in place by screwing onto the threaded rod on the other side of the spider vane. Using a small crescent or appropriate sized box-end wrench, loosen the nut on the back side of the secondary. Once it's loose, reach through an opening in the spider vanes and grasp the BACK of the secondary. Make sure you grab the back of the secondary or grab it at the top were the threaded rod protrudes from the spider vane. Be careful not to touch the optics. Completely remove the previously loosen screw the pull the rod out of the spider vane mount by pulling the secondary assembly down. Set it aside with the primary.

5) At this point, you have an OTA with no optics. Next remove the focuser. If you are still using the standard Meade focuser, it has four screws that hold it in the OTA. Each bolt has a small nut mounted on the inside of the tube. They are easy to see if you look into the tube from the spider vane end. Rack the focuser all the way out, remove the four bolts with a screwdriver and a pair of needle nose to hold the nuts. Gently pull the focuser off the OTA.

6) Can take an hour or so to greatly improve the scope with a very simple modification. But this step is strictly optional. Take the tube outside and remove the finder from its bracket. Get some dull black spray paint. Heat resistance paint, such as used on BBQ grills, works great. Take a 9" piece of string and tie it around a pencil. Hold the other end in the center of the hole the focuser was mounted in, and use the string like a compass to mark of an 18" circle around the focuser. Mask around this circle with newspaper and tape, then paint the whole area around the focuser dull black. You'll get a lot less glare from that shiny white tube in your peripheral vision. If you do this step, let it dry at least a day under a fan.

7) Now we'll prepare the optics. In this step we need to mark the center of the mirror while maintaining its reflectivity. The laser is going to strike the secondary, bounce off it and hit the center of the primary. As part of one of the collimation steps, you will adjust the secondary to make sure the laser strikes the exact center of the primary. One of the best ways to do this is to get those adhesive backed rings used to reinforce holes in notebook paper, and place it on the center of the primary. This won't cause a problem with your optics since the center of the primary is in the shadow of the secondary when properly collimated.

To find the center of your primary, start by respecting your optics. Keep everything off it. Fingerprints are nasty to remove. Forming a triangle, the mirror is held to the mount by three clips. Using sewing thread, tape a piece of thread from each clip to the two clips opposite of it. Keep the thread taunt by not especially tight. This forms a triangle of thread. Keep the tape and the thread off your mirror. Using a ruler, measure the length of thread going from one clip to another. Note the center and mark it with a tiny piece of tape. Do the same with another line of thread between another two clips. Now for each piece of tape marking the center of a line, go to the post opposite and attach a piece of thread long enough to cross the whole mirror. Tape one end of it to the mirror post opposite the center mark on the other side of the mirror (on top of everything else), and lay the remainder on the table. Do this to the other clip opposite the other center marker. Now stretch the two pieces of thread across the mirror and line them up with their respective center markers on the line opposite the clip they are attached to. Where the two lines bisect is the center of the mirror. Mark it (another person is invaluable here) right under the intersection of the two bisecting threads with a non-permanent felt tip marker. It doesn't have to be especially dark. This is the center of your mirror.

With tweezers carefully place the adhesive ring around the spot marked on your primary. The reinforcement ring's center hole should surround the dot on mirror and the dot should be centered in the ring. Press the ring down firmly. Use some rubbing alcohol (very little) on a Q-tip to gently remove the marker dot from the center of the ring.

You also need to find the center of the secondary. Since it's much smaller you can use a millimeter ruler and measure both ways. You can't, of course, lay the ruler on the optics. I did this by mounting the secondary on my workbench so the mirrored surface was face up and level. I carried my measurements a few millimeters above the mirror by hand, and marked the center with a non-permanent marker. Even though you see the center of the secondary, it is only looking at the shadow of itself on the primary, so once again, the small dot from the marker isn't a problem on the optics.

8) Time to square and face the focuser. Measure the outside diameter of the OTA up against the outer rim to get a good accurate measure. Better yet, get some dry wall tape or some cash register tape, and wrap it around the tube, cutting it exactly to the proper length so the two ends just meet. Fold the tape exactly in half to find the median. Or just use your measurement to determine the center. Wrap the tape around the tube with the center fold centered over the eyepiece hole. Where the two ends meet on the other side is the exact opposite of the tube. Mark it with a pencil. If you measured, make certain you keep the tape the same distance from the end of the tube (make a lot of little measurements down the length of the tube) and determine where the opposite side of the tube is.

Now measure from the secondary end of the tube to the center of the focuser hole. Let's call this number A. Now on the exact opposite of the tube measure down the tube from the secondary end a length of A (where you marked earlier). Mark this on the scope with a pencil. Your two lines should intersect. One showing half the distance around the tube from the center of the focuser hole, and the other the distance down the tube to the center of the focuser hole. Force a needle or pin through the side of the SonoTube until it just penetrates the inside so you can see it. This is the spot exactly opposite of the focuser. The focuser should be exactly square to this. Mark this spot on the inside of the OTA with a dab of White-Out, white paint, or an adhesive white paper circle.

While you have the focuser off, take some liquid, not gel, super glue and squeeze it into the exposed cardboard sides of the holes the focuser fit into. Get it nice and wet in all four holes, all the way around the inside. You want the cardboard to soak up the glue and reinforce a larger area then the hole. Since you're there, do the same thing with both sets of holes that the primary mirror mounts into (both the visual and the photographic position). This makes the holes make tougher and less prone wear which will cause wiggling of the focuser or mirror. Let this dry.

Put the focuser back on the scope, but only tighten the bolts tight enough to hold it square. Put your laser collimator in the focuser and turn it on. It will project a red dot to the other side of the tube, hopefully directly on top of the white dot you placed there. Now you need to start tightening down the focuser and either use the focuser adjustment screws or shims to fully tighten down the focuser while keeping the laser's red dot on the white spot. Once done, make sure the focuser is nice and tight and that the laser still projects it's dot on the white circle on the other side of the tube. The focuser is now square.

9) Calculating the offset. For Newtonian optics, it is necessary to offset the secondary mirror both away from the focuser and towards the primary mirror to fully illuminate the edges of the field. This is due to the 45 degree angle of the secondary causing one side of the light cone to be bigger.

To calculate this offset use the following formula:

S = secondary mirror minor axis
D = diameter of primary mirror
F = Focal Length
O = one half of the outside diameter of tube H = focuser height from the bottom to a fully racked in focuser
I = "in-travel" distance of focal plane above fully racked in focuser
L = O + H + I
offset = S * (D - S) / 4 * (F - L)

So for my 10" with a low profile Crayford focuser L is (all measurements in millimeters)

L =152.4 + 38.1 + 76.2 = 266.7
S is 60.198 (standard)
D = 254 (standard)
F is 1140 (standard)

So my offset is 60.1 ( 254 - 60.1) / 4 * ( 1140 266.7) = 3.3 mm

This offset is divided in half. One half is applied to move the secondary away from the focuser and the other half moves the secondary towards the primary.

10) Re-center the primary. Replace the primary mirror by aligning the dot on the mirror with the dot on the tube and place the mirror in it's normal position (I always used photographic). For non-StarFinder Newts it's important to make sure the mirror is centered on the mount and mount is centered in the mirror box. With the StarFinder's, you can't adjust this. Meade does an excellent job though. (I've done this procedure on about 12 different StarFinders and all are centered extremely well).

11) Square and offset the spider. If you have a four vane spider, you can usually hold the laser collimator on the surface of the spider with the laser shooting through the hole the secondary normally mounts in. Hold it carefully so the spider is not compressed. Make sure the collimator is level against the spider and see where the laser strikes the primary. BE CAREFUL, the laser will reflect off the primary and back out the front of the scope if the primary is not aligned properly. Do it from the side and hold something up in front of the scope first to determine where the spot lands outside the scope. You don't want it hitting you directly in the eye. Turn on the laser. Look to see where the laser strikes the primary. If hits the center of the mirror in the adhesive ring, you need to do anything except apply the offset.

To square the spider vane, you need to move the spider until the laser hits the center of the ring you placed on the primary earlier. If this is off by more then 1/2", you need to check the primary mirror in the mirror box. The spider is held in place by four screws into the tube. To move the spider, loosen the screw on the end of the spider opposite of the direction you want it to move, and tighten the one in the direction you want it to move. Due one axis at a time, making small moves. Check with the laser often, and keep going until the laser strikes the center of the primary. If the spider stops moving and it's not centered at any point in this process the primary is not center in the OTA.

Once the spider is square you need to apply half the offset to move the secondary away from the focuser. Most Newtonians mount the focuser on the same axis as on of the spider vanes. This is the case with all the Meade's I've seen (it's a good design). For most 6" to 20" Newts this offset is small (around .5 to 3mm), so a couple of turns on the screw opposite of the spider opposite of the focuser is all that it takes. Remembering you're applying half the offset, so in my previous example, it's 1.65mm. Finish by loosening the spider mount screw on the focuser side of the vane by the same number of turns.

12) Replace and offset the secondary. This is the toughest part. put the secondary back in the spider and replace the outside nut that holds the secondary in the spider vane. Tighten it to secure the secondary but make sure you can rotate the secondary.

Look in through the eyepiece. You should see your eye, the reflection of the primary on the secondary, and the reflection of the secondary on the primary. It's all a bit of mirrors without the smoke and kind of fun to do. Now for the rest make sure your eye is centered in the focuser. This is easiest to accomplish by using a 35mm film canister. Drill a small hole in the very end of the canister. Most film canister have a little dimple on the bottom. Drill this out. Cut the canister below the rim that holds the cap on and it will now fit in a 1.25" focuser or 1.25" focuser adapter. Look through this tiny hole. It will guarantee your eye is centered on the secondary.

Looking through this perform the following:

A. Rotate the secondary until the reflection of the primary is centered all the way around.
B. Move the focuser in or out until the edge of the primary is just seen on the secondary. When the primary is centered, tighten the secondary in place.
C. You should see your the film canister surrounded by the secondary, surrounded by the primary, all centered.

With that done, remove the film canister and place the laser in the focuser. Once again, it's important to realize the optics aren't aligned and it's possible that the laser may shoot out the end of the open tube. BE CAREFUL. Look inside the open end of the OTA to see the reflection of the secondary in the primary (your look at the primary) to see where the laser is striking the secondary mirror. If it's right on top of the dot you placed on the secondary you only need apply the offset. Otherwise, you can adjust the secondary. Out means towards the front of the scope and in means towards the primary. Move it out by turning the screw on the secondary side of the threaded rod counter-clockwise and turning the nut outside the spider vane clockwise. Move it in towards the primary by doing the opposite. To adjust left and right, rotate the secondary in the holder. When the laser strikes the secondary on the dot, it's time to apply the offset.

You want to apply half the offset calculated in step 9 to move the focuser towards the primary. This means moving it in by loosening the nut inside the spider and tightening the nut outside the spider. Once again this is a fairly small distance, so a few turns is all it takes. To be very accurate, you can measure the distance between threads on the threaded rod, and how many turns of the nut it takes to make a full rotation by counting the threads inside the nut. Otherwise, use a ruler to the best of your ability held up to against the inside of the spider vane. Once the secondary is in place, check it's position again with the laser (it should be slightly on the "out" side of the dot now).

You can now remove the dot from the secondary with a little alcohol and a Q-tip (use the weight of the Q-tip to do the job). On large Newts (16"+) may no longer be in the shadow of the primary. We're nearing the end.

13) Adjust the tilt of the secondary. On the back of the secondary are three screws. These work like the wing nuts on the back of the primary. It allows you to adjust the tilt of the secondary. Put the laser back in the focuser and turn it on (CAREFUL AGAIN). Look inside the tube to see where the laser is striking the primary. At this point, the laser strikes the secondary, is reflected to the primary, and is reflected back to the secondary. If the mirrors are way off, it may not hit the secondary the second time.

In this step the goal is to get the laser striking the center of the primary inside the ring placed there earlier. Using a Phillips screw driver, gently adjust the three screws on the back of the secondary to get the laser striking inside the center of the ring on the primary. The laser may still not hit the secondary again because the tilt of the primary is not yet adjusted. Just make sure the laser coming off the secondary strikes the center of the ring on the primary.

14) Last step, adjust the tilt of the primary. Rack the focuser all the way in. Hopefully the focuser tube will stick out of the bottom of the focuser. Take the cap from the film canister. Drill out the exact center to make a 1/4" hole. Place this on the end of the focuser (1.25"). It will fit it perfectly. Place the laser in the focuser and turn it on. Since we haven't adjusted the primary, it is important to be careful when looking in the scope. Look in the scope so you can see the bottom of the focuser. The laser will exit the hole of the canister lid, strike the secondary, bounce to the center of the primary, bounce back to the secondary, and finally hit the bottom of the film canister lib again. This means you should see a dot on the film canister. Remember (you've been careful right?) the laser may be missing the secondary on the return trip and exiting the front of the scope. If it is, start adjusting the wing nuts on the back of the primary until you see laser strike the secondary again. On the 10" and larger you can usually look through the gap in the mirror mount to see the dot on the bottom of the focuser.

This is how the scope will normally stay after the first time. You are now rough aligned and have a red dot on the film canister lid on the bottom of the focuser. The object is now to further adjust the primary until the red dot on the canister lid disappears into the hole in the center. I always get my willing wife or a star party attendee to watch the dot as I move the adjust the primary. With practice all you need is "left, right, up, or down" from your partner, and you'll be able to place the red dot in the center of the lid where it will disappear entirely.

>From now on out you will probably only need to perform step 14, and occasionally 13 as the scope is jarred during travel or setup. In 2 years of laser collimation, I have only done steps 13 twice (initial setup, and one other time). Step 14 takes about 30 seconds, and I do it at the beginning of every observing session, and sometimes a few times in the middle.

Now you have prefect Newtonian collimation in about 30 seconds any time you want.


Subject: Magellan II Star Charting Software    Top

From: Joe Longo <sthnstara_tsouthernstars.com> Date: Oct., 1998

If you have a Magellan you should run SkyChart III. SkyChart's user interface is ideal for scope support and field observing. The latest version also prints superb finder charts, and even plots the scopes field of view on the chart. You an download a fully functional demo from the skychart web site:

  <http://www.southernstars.com/skychart> Note: should open a new browser window over this one.


Subject: Magellan II Operation Hints  Top

From: M. Searle < msearlea_twest.raytheon.com> Date: Sept., 1998

After some teething pains, I've generally been quite happy with the Magellan II; I have a 16" Starfinder Equatorial, and it makes life much easier when looking for faint objects. If one follows the directions (plus some hints) the M-II will put an object in the field at 80X every time. Other products are less expensive, but the M-II is made-to-fit.

The Hints:

  1. Check all of your (and Meade's) connections, especially the encoder connectors (solder 'em!). If you center a star, the raw encoder counts (before you do an alignment) should always end up where they were after moving the scope around; this will also show up any looseness in your mount or optics.
  2. I use a one-star alignment, then sync to a star near your first object. Definitely use an eastern-sky, meridian star for the first/only alignment star. Meade has a short list of alignment stars (30), but as far as I can tell the entire LX200 object database is in there for syncing on. Doc Greiner's homepage has detailed database info/links. You can get away with using any two of the three alignment steps in Meade's instructions (pole and two stars) if it's cloudy.
  3. The encoder gear ratios (just the signs) differed from what Meade gave me; an hour of at-home experimenting using the mount's setting circles to fake-align the system will tell you if the ratios are correct & give you good practice besides.
  4. Make sure Meade gives you a "1K" R.A. motor (not a "500", as stamped on the metal gear housing). I've seen other posts that emphasize the need for this without my really knowing why; Meade also acknowledges this & will send you a "1K" motor without hassle.
  5. The advertised "GoTo" function is supposed to slew the scope the final 2 degrees or so onto an object (but doesn't). Meade will fix this "soon" in a new S/W release, but I prefer manually centering anyway to minimize fussing with the tangent arm, etc.
  6. The M-II doesn't actively correct (operate) the axis drives, but does display the true pointing coordinates (the Dec reading will change more or less rapidly depending upon your mount's mechanical polar alignment). Meade's advertising and even the manual are misleading on this feature.
  7. Use an external power source (12V); it runs the motors faster and I got tired of buying AA batteries.
  8. I have just tried the updated Earth Centered Universe program <http://www.nova-astro.com/> on a laptop; it worked well with the M-II in the field. The M-II uses only three LX200 commands; ACK, :GR#, and :GD#. The serial port needs to be manually enabled first.
  9. I like being able to store your own objects; you can punch them in before an observing session.


Subject: Starfinder Rotating Rings Source Top

From: Jeff Gibbons <Jgibleulera_taol.com> Date: Feb 2001

I read that someone was looking for Rotating Rings for Meade Starfinders. Someone may have already answered this question but they are available at Parallax Instruments. I've had them for about three years, they work well and really do eliminate the problem of getting to the eyepiece. I use a bar stool for seating and rotate the tube to me. This makes viewing very comfortable.


Subject: Meade Starfinder Contact Person / Starfinder 16" Discussion Group  Top

From: <Torq460a_taol.com> Date: Dec 2001

For questions re: the Starfinder line of scopes we owners have a friend at Meade: call Paul McDaniel. He is far and away the most knowledgeable about our scopes. See Meade topic for phone numbers.

Also be advised that there is an owners group on Yahoo dedicated to the 16" Starfinder DOB and EQ. Great,source of advice and ideas:


MAPUG-Astronomy Topical Archive   AstroDesigns   Top   MAPUG-Astronomy.net