Pictor 201/216XT -- Getting Started

       

 

Subject: Pictor 201XT-- Getting Started   

From: Michael Hart

I have received several private requests for specific and general autoguiding information that pertain to the Pictor 201XT. The 201XT at around 8 ounces is arguably the lightest autoguider available that may well be an excellent choice for off-axis guiding due it's light weight that minimizes off-axis guider port flexure problems. This helps when you use a reticle eyepiece such as the Meade 9 mm that is very close to parfocal with the 201XT autoguider to center the selected star. With the light 201XT, you can remove the guiding eyepiece and insert the 201XT that results in star coordinates indicating the star very near the center of the 201XT CCD chip. Heavier autoguiders designed for separate guidescopes often cause enough flexure on off-axis guider ports that finding the star on the chip at all can prove difficult. It is not cooled, which reduces power consumption considerably at some expense to the higher magnitude guidestars that can be used. Still, I find that if I can see the guidestar, I can guide with it using the 201XT.

Preliminary preparations: Obtain a 12mm or 9mm reticle eyepiece. The 201XT, 208XT and 216XT are close to or parfocal with a Meade 9 mm illuminated reticle. Check the time it takes a star to move a fixed distance in the eyepiece using the guide mode. On the 201XT, you will use this to adjust the RA and DEC calibration time from the default values of 2. If your DEC time takes a little more than twice as long as the RA time to move a fixed distance, set the DEC calibration time to 5 on the Pictor 201XT. Leave the 201XT plugged in to warm up properly (about 10-15 minutes). The power-up mode for the 201XT is "FF" on the LED (light emitting diode) for "Find & Focus" The 201XT uses one button to access all modes via a "short keypress", "medium keypress" and "long keypress". Verify you can know how to move between modes and set exposures. Copy and laminate the flow chart in the Pictor 201XT manual. This will be useful until you memorize how to get from mode to mode.

Those that do not own a 416XT or 1616XT may need 1-1/4" eyepiece extensions available through Meade small parts or as the Lumicon LAD110 eyepiece extension. If you own the 416XT, you have the eyepiece extensions and lock rings to make a parfocal eyepiece for the 201XT.

First, rotate the off axis guiding port perpendicular to the DEC bearings (straight up) and insert a 12mm fixed reticle eyepiece. Those with movable reticles will want to center the reticle and check centering by rotating the eyepiece around a star. Move the scope until a fairly bright star AT ABOUT 30 DEGREES DECLINATION appears in the guiding eyepiece. Use the focus knob to focus, then center the star under the cross hairs. With a LX200, you can note the RA & DEC coordinates for return to your star, if needed.

Next, focus the Pictor 416 as usual through the off-axis guider using the supplied off-axis guider extension for the Pictor. If you intend to use the Pictor rotation adapter, install this now. If your using a camera, remove the off-axis guider extension and install the proper T-ring for your camera and install your camera. Of coarse, your guide star will not be visible on the Pictor chip and possibly only in the diagonals of your camera viewfinder as it is "off-axis", but most likely other stars will allow you to focus your Pictor 416XT. Do this now using the focus knob. Finish the last 1/4 turn counter-clockwise. If your using the Pictor 416/1616 with the orientation adapter, you can remove the Pictor 416/1616 and insert your 26 mm eyepiece that came with your scope until focus is reached and mark the eyepiece barrel. You now a wide field eyepiece that is parfocal with the Pictor 416/1616. DO NOT TOUCH THE FOCUS KNOB!

If your using a camera, you may have to move the scope to a find a suitable star to focus on. If your familiar with knife edge focusing, rough focus through the viewfinder and remove the camera and T-ring and install your knife edge focus tool now. Those that lack such a tool can open the back of the camera and tape a common safety razor blade parallel to the film plane. Moving the scope in RA guide speed until the star is "cut off" instantly by the knife edge means you have a pinpoint star and perfect focus at the film plane. If out of focus, a dark curtain will appear and move from one side to the other. As you get closer to focus, the curtain tends to descend from everywhere. Perfect focus shows a bright star that is almost cut-off instantly by the knife edge or Ronchi grid, going from light to dark as you move the scope. The use of a razor blade is meant to demonstrate the theory, so BE CAREFUL! Please buy the appropriate device.

Return your scope to the noted RA & DEC coordinates now, if needed. Check and re-center the star in the off-axis guider port. DO NOT touch the main focus knob. Instead, move the reticle eyepiece up and down to reach focus. If necessary, add an extension to reach focus to re-center the star. Remove the reticle eyepiece and insert the Pictor 201XT into the guiding port. Since you centered the star with the reticle, the star should fall on the 201XT chip as the 8 oz 201XT is only 2-3 ounces heavier than the guiding eyepiece. Those with heavier guider/imagers such as the 208 & 216 may need to add weight around the guiding eyepiece to equal the heavier cameras to assure the star falls on the imaging chip precisely. For now, orient the Pictor parallel to the back of the scope (RA axis). The guide port is still perpendicular to the DEC bearings (straight up) that you set earlier.

If you have the Meade 9 mm reticle, you can use this to rough focus the 201XT. If the 9 mm reticle is 1/8" from full insertion, set the 201XT 1/8" as well. If you don't have the 9 mm reticle (which has the downside of needing the reticle centered), you will want to create a parfocal focusing eyepiece AFTER you focus the Pictor 201XT to ease focus in the future. Set the exposure time for 3 seconds and take the appropriate dark frame. Now, initiate a short press to engage the "br" (Brightness) followed by "00" to "99" (the amount), then "At" (for at) "00" to "99" (the first digit indicates the stars X location on the chip. The second digit 2nd digit indicates the stars Y location on the chip). A 44 to 55 reading indicates the star is centered on the chip. On your scope with the Pictor oriented as outlined, the fist number is RA and the second number is DEC. For now, ignore the "At" readings until the Pictor is focused.

If you selected a fairly bright star, a 3 second exposure should indicate brightness ("br") readings of at least 20. If you get 90-99, reduce exposure and take a new dark frame. Now, move the Pictor up in the holder by 1/16". The brightness readings will increase as you approach focus and more star light is focused on fewer pixels. When the brightness ("br") readings go down, you have passed the focal point. Move the Pictor in the holder for the brightest reading. When brightness levels start to change much more rapidly, you are very close to focus. Move the Pictor in very tiny amounts at this point. At the point of maximum brightness ("br"), mark the exact location of the Pictor barrel. A focus ring is then placed at this exact location to enable repeating focus.

It is time to make your centering eyepiece parfocal with the Pictor which will vastly simplify future star centering and focus. Insert your 12mm or 9 mm reticle and move up and down until the guider port target star is in focus. Add extensions and a focus ring as needed to mark and maintain the exact eyepiece position. In the future, you will use this to find and center your guide star for the Pictor.

Now is a good time to teach your Pictor about your scope by using the Calibrate mode. Since you picked a star at about 30 degrees declination, your Pictor can be calibrated to guide well on objects from -60 to +60 degrees declination and will retain your calibration after the power is removed. Using the E & W keys for RA and the N & S keys for DEC, center the guide star, if needed for a "At" reading of 44 to 55. Now is the time to verify you have the Pictor plugged in to the CCD port on your scope. If your using the Pictor 416/1616, verify you are not using the RS-232 port/ serial port cable rather than the correct cable. The wrong cable will result in continuous DEC motor running that stops when the cable is removed from the scope or Pictor. Enter the calibration mode with a medium press from the focus mode. A "CA" will appear indicating calibration is about to begin. The display will indicate "FS" (Find Star), then "rt" (Right), then "FS", then "LF" (Left), then "FS", then "UP" (Up), then FS, then "dn" (Down) and finally end in the "gd" (Guide Ready) mode.

You have completed motion calibration of your Pictor to your scope. Now the Pictor knows directions and guide correction speeds. All motion calibration information is permanently stored. What if you find you need to rotate the guiding port to find a guide star? Here is an important rarely mentioned tip for using the autoguider in a different orientation than was calibrated: Rotate the autoguider in the same number of degrees and direction as you rotate the guiding port around the optical axis. In this way, your Picture's memory for directions agree with the star movements in the guiding port WITHOUT RECALIBRATION!

A single short or medium press at this point starts the Pictor guiding. The display will cycle "gb" (Guide Brightness), then the 2 digit brightness level, then "gc" (Guide Correction), then the 2 digit correction level, the first digit being RA and the second being DEC and finally back to "gb". Guide brightness levels of 30-60 help assure the guide star won't disappear if a slight haze appears. Guide correction "gc" levels 10, 20, 00, 10, 01, 10 indicate the Pictor is tracking well with most of the correction made in RA because the scope had good polar alignment and hence little declination drift to correct. Guide correction levels that jump around will most likely result in spoiled images. Guide correction levels that stay at 00 also indicate trouble. You can practice by using the scope with a reticle eyepiece to verify tracking.

201XT key points:

Let the 201XT warm up for 15 minutes before starting your image exposure. Use a parfocal eyepiece to rough focus (The Meade 9 mm reticle is close). Tweak focus to achieve maximum br (brightness). Keep exposure times below 90 br. Take a dark frame prior to imaging. Don't forget to motion calibrate your autoguider so it knows directions. Use a RA calibration time of 2 and a DEC calibration time of 5 (page 2-16). For general guiding, perform motion calibration at about 30 degrees declination. Don't expect any autoguider to produce good images under wind and poor seeing.

-- Michael Hart, Husen Observatory

Subject: Re: 201XT FOV  

From: John Hoot <jhootexo.com>

The field of view (FOV) at various focal lengths for a 201XT guider are as follows:

F.L.            W      H 

2000mm   5.5'   4.1' 

1280mm   8.6'   6.4' 

In general width is arctan = (3.2/FL) where FL is the focal length in mm. The height is 0.75*width. The field of view of you eyepiece can be determined by turning off you scope drive and timing the drift time for a star near the celestial equator to move across your eyepies.

Stars at the equator appear to move 1 arc minute every 4 seconds.

Pictor 201XT-Description of the Calibration Process   

From: SB635delphi.com

Since I've not yet seen any description of the calibration process on this list, I'll take this chance to give a brief description of how I understand it. This will make it clear as to why centering is important.

During a calibration, an autoguider first digitizes the frame and computes the centroid of the calibration star on the chip. This gives an (x,y) location of the star in terms of x pixels by y pixels. The autoguider then speeds up the RA drive faster than sidereal for so-many-seconds. The so-many-seconds is user definable (I usually use 5 seconds). This, naturally, moves the star to a new location on the chip. The image is then digitized and the star's new centroid position is computed. The autoguider then computes a velocity in the x-direction as the delta-x pixel shift divided by the time the RA axis was sped up. It also computes a velocity in the y-direction using the delta-y pixel shift. The autoguider now knows that if it issues a so-many-seconds RA speed up, it will move a guide star by the corresponding amount, and in a specific direction. This entire process is repeated for a so-many-seconds RA drive slow down, for a so-many-seconds north DEC movement, and for a so-many-seconds south DEC movement. In the end, velocities (in terms of pixels/sec) are computed for all four directions (fast/slow RA, north/south DEC). Effectively, the autoguider has "trained" itself about how to guide.

After the calibration, an actual guiding can now be done. The basic process is: A guide star is placed on the chip and its centroid is computed. The first guiding cycle is started by taking an exposure and computing the shift in the (x,y) pixel position of the star's centroid. The observed shift is used with the calibrated velocities to figure out: 1) whether to speed up or slow down in RA and for how long, and 2) whether to go north or south in DEC and for how long. The autoguider then issues the correction commands to the RA and DEC drives, and the second guiding cycle is initiated, etc.

From the description of the calibration process, I think you can see why it is so important to center the calibration star. By centering the star, the autoguider has as much room as possible to work with in all 4 directions. A too-long-of-a calibration time can easily move the star off of the chip, and the calibration then fails. I think you can also see that a "+" pattern is produced by the various star positions. I use SkyPro with my ST-5, and it will fail a calibration if the orthogonality (i.e., right angledness) of this pattern is violated to some degree. The degree of orthogonality you get has everything to do with the orthogonality of the RA and DEC axes of your mount, how orthogonal your optical axis is to your DEC axis, and also the quality of your RA and DEC drives.

Subject: URL--Using the Pictor 201XT      

From: Guido Pasi, Date: Dec., 2003

The Pictor 201XT is really a debated object, for this reason I thought to add a new page to my web site about using it. The URL is:

<http://spazioinwind.libero.it/gpasi/tech/201xt/201xt.htm>
Note: should open a new browser window over this one.

You will find:

-some general considerations about setup
-the description of the main faults with my workarounds
-a diagram about relationship between guide star mag. and exposure times of the CCD
-a diagram about the precision required in focusing
-a new "mode diagram", quite similar to the Meade's one, but complete and correct.

I hope that someone could find this useful.

Subject: Setting Up / Using a Pictor 216 CCD   

From: Graham Warrellow, Date: Jan., 2000

Kevin Sterling wrote:

>> Any tips on using a Meade 216? tried mine the first time last evening
>> and all I was able to get was streaks (vertical) of light!

Let's take it one step at a time! First try using it to image a distant object in daylight. I remember using a distant TV aerial first time out. The benefit of this is that no tracking is required and you can get to grips with the PictorView software. I suggest you download version 6.45 from the Meade website (forget PV 7.0! for the time being!). It will also get you close to the all important accurate focus point. You can use this as an opportunity to create a parfocal eyepiece. You will need to stop your telescope down to a couple of inches using a cardboard off-axis mask otherwise the daylight image will be over exposed.

Take a look at Thierry's website for excellent general CCD advice:

<http://perso.club-internet.fr/legault/>
 Note: should open a new window over this one.

If you look at Glenn's astrophotos you will see that he is also successfully using the 216 as a stand alone autoguider with his 12" LX200.

BTW the vertical streaking is probably due to overexposure (vertical blooming). You have essentially overfilled the pixel well and it's flowing over the sides.

I would suggest that once you are comfortable with your daytime images, shoot the moon then Jupiter or Saturn. When you master those move on to globular clusters and stars where tracking becomes much more important! Be patient, in fact you need to be very patient with the Pictor 216 because of the very slow download times. The 216 will produce excellent images but IMHO is not the best value for money imager at that price.

Subject: ETX and 201XT, 208XT, or 216XT Autoguider Primer    

From: Donald Tabbutt <dontabbutt.com>

This is a primer on using the ETX as a guide scope with a 201XT, 208XT, or 216XT autoguider. It is a compilation of many posts and responses. Some parts include a computer for imaging, but only for centering purposes during initial setup. If you have a 201XT, use the instructions in your manual for centering. This primer takes advantage of the ETX's flip mirror system to find, focus, and center a guide star. Thanks to all who contributed to this post, in particular Doc G, Howard Anderson, Ric Eckler, John Hoot, and others.

You will need:

• A 201XT, 208XT, or 216XT, which I will refer to as the "guider" in this post.
• An ETX optical tube assembly.
• A piggyback mounting system...I use the Losmandy D-Mount with rings.
• The standard 26mm eyepiece and the locking ring that came with your guider.
• Meade #64 T-Mount adapter for the ETX.
• Meade 9mm Illuminated Reticle eyepiece.
• A computer running Pictorview X.x connected to the 208XT/216XT (optional).

Initial (one-time) Setup (time consuming, but worth the effort):

• Mount the ETX and carefully collimate it to the main telescope with its eyepiece port "up".
• Attach the guider to the ETX as follows:
• Unscrew the nose piece from the guider.
• Unscrew the ring the nosepiece screws into from the guider.
• Screw the front half only of the #64 T-adapter into the guider.
• Remove the dust cover from the rear of the ETX.
• Mount the guider to the rear of the ETX. Be sure it is upright (power
• cable straight down).
• Connect the appropriate cables.
• Attach the locking ring to the 26mm eyepiece such that 3mm (1/8 inch) of the shiny barrel shows through between the stop of the eyepiece and the locking ring.
• Insert the 26mm eyepiece into the top of the ETX and flip the mirror up.
• Focus and center (N, S, E, W keys) on a fairly bright star. Flip the mirror down and cover the eyepiece.
• Using Pictorview, image the star, and using the N,S,E,W keys, repeatedly image it until it is centered. On a 201XT, or if no computer is available, center it per the guider's manual. Recheck the ETX's collimation with the main telescope at this time. Repeat if necessary.
• Flip the mirror up and insert the 9mm reticle eyepiece. Refocus on the star.
• Be sure the reticle eyepiece is oriented with one reticle adjuster straight forward (dec) and the other to the right (ra). Move the adjusters until the reticle is centered on the star. Don't touch the reticle adjusters from now on.

You now have a parfocal eyepiece (the 26mm), and a fine centering eyepiece (the 9mm reticle).

Guiding:

• Center the main telescope on the target to be photographed.
• Insert the 26mm eyepiece into the top of the ETX.
• Flip the mirror up and focus.
• Adjust the piggyback mount to find a guide star.
• Center the guide star using the piggyback mount adjustments.
• Insert the 9mm reticle eyepiece into the top of the ETX (remember orientation).
• Refocus and finely center the star using the piggyback mount adjustments (don't touch the reticle adjusters).
• Re-insert the 26mm eyepiece and refocus.
• Flip the mirror down.
• Cover the 26mm eyepiece.
• Follow the guider instructions to set exposure, dark frame, calibrate, and start guiding.
• Shutdown of the 208XT and 216XT:
• From Gd, enter a medium press.
• From FF, enter two short presses to reach Gd, then a medium press.
• The display will read Cv, where v can be from 0 to 9.
• Wait until the display reads C0, then unplug the guider.

This is an important step to protect the CCD from rapid warm-up.

Tips:

• I've never needed an exposure longer than 1 second on any guide star to mag 9+ with a 208XT.
• Reset the LX200 declination backlash before each exposure...orientation changes it.
• Balance the main telescope for each photograph.
• Always take a dark frame.

Subject: Solving 201XT Guiding Problems    

From: Ralph Pass <rppassrppass.com> Date: Feb 2004

Alex wrote:
> I posted a mail concerning my problems in autoguiding with a 201XT.
> Some of you answered me that my main problem was the mirror flop of the
> OTA (Meade 2045) piggybacked to the main OTA (10" f 6.3) and that cause
> some guiding error due to this movement.
> But i started to solve my problem starting from another point of view. I
> saw that just after 10 min of guiding the problem was jumping out. I also
> started to think why use a Et of 0,5 sec, if with this interval the star
> is almost in the same position (also with a worst polar alignment). I was
> on the right way; it could be possible that with a so short time the 201
> firmware is not able to take the data of the chip, elaborate it and send
> the corrections to the scope. That's it.. Using Et of 3 the CCD is guiding
> correctly with the same configuration.
> After 5 years, lots of cold night and picts moved... The problem is not
> mine (a part using a wrong Et) but of the firmware...
> My questions are now:
> - does Meade think that with too short Et the CCD is not working correctly
> - Others of the group had the same problem and the same solution?

When you line things up and are about to start guiding, you need to short press to get the 'br' display. You want this number to be at least 15 before starting to guide.

Once you have a number bigger than 15 (by changing stars or by changing et and doing another dr) you can then start to guide.

Just for information, when guiding you will see a cycle of 'gb', a number, 'gc', a number etc. Each display is a guiding update so you get four updates per each cycle.

I use mag 5 guide stars and have et set to 0.1. This works fine, so I do not think there is a firmware problem with shorter exposures. There could be an issue if the seeing is poor. This would cause a star to 'move' about on the CCD chip (which the 201 or any guider will try to track) If so, you can then adjust the seeing parameter from 0 to 1 to reduce the jitter.

Subject: Pictor 201XT-- Guidescope or OAG?    

From: Greg Hartke <ghartkeclark.net> Date: Jan 2001

> Alan Voetsch wrote:
> My 201XT would still be sitting in my closet if I'd never read
> Guido's article in the Archives. Once again, thanks Guido.
> Greg's set up interests me as I've been considering using a guide scope at
> some time in the future. I've pretty much always heard that with
> a SCT, off axis guiding is preferred. That's what I've been doing.
> I'd like to ask the 201 experts out there what their minimum focal length
> recommendation would be to guide a 12" LX200. FYI, they've got a 3048 mm f.l.

Hi, Alan, Guido's article and the info on Guido Pasi web site at:
   <http://spazioinwind.libero.it/gpasi/> is really good, isn't it? Note: use Techniques link

A guidescope can be made usable but you really have to work at it. As you would expect, the success rate varies inversely with the length of exposure. Really short exposures in the 30 minute range are hardly a challenge. Successful exposures of 60 minutes are harder. I do a lot of exposures at 90 minutes and that's *really* a challenge. I seem to go thru spurts where my success rate is high, then a series where it's low. I have plenty of good 90 minute shots but also plenty of bad ones. It's worth keeping in mind that I use a 10" f/6.3 LX200. Obviously, the situation would become more difficult with longer focal lengths. In addition, I would recommend against this approach with the 8" scopes because you can't lock the primary mirror in place.

For others considering this option, it's worth examining why I opted to try the guidescope approach.

(1) Cost: I was able to obtain an 80 mm f/11.4 Celestron refractor OTA (with locking focuser) from Gary Hand of Hands on Optics for $165. The 201XT was bought new for $400. Scope mounting rings were another $135. (I already had a dovetail mounting plate.) For comparison, a GEG is $400. Many users had said how terribly the 201XT worked with OAGs, so I assumed an ST-4 was necessary. Cost: $900. In addition, I assumed (possibly incorrectly) that a laptop would be necessary to use the ST-4 to its full advantage. In particular, I figured it would be almost a necessity for focusing. The advantage of the 201XT was that I knew it was parfocal with the Meade 9 mm reticle EP (which I already had), making focusing very easy. On balance, it looked as if a guidescope setup would be significantly less expensive (a minimum of $600) than going with the GEG and that was important. As I've said before: Sometimes the wallet will only stretch so far.

(2) From an operational standpoint, I expected a guidescope to be *much* easier to use than an OAG.

(3) The guidescope can be used on future instruments. The LX200 is a really nice beginner to intermediate AP package but I have no intention of staying with this instrument forever. The guidescope and rings will likely be used for a very long time after my LX200 is history.

(4) Experience: I've been an amateur astronomer since Hector was a pup (over 30 years) and am technically and mechanically oriented. My research on the subject did not lead me to believe that the failure of people attempting to use a guidescope with an SCT was entirely definitive.

So what have I learned in the course of a lot of exposures over a fairly long time? Well, I remain pleased that I tried this approach. It can certainly be done with this instrument but (as I've said before) it's not really for the faint of heart. Still, I'd prefer a higher success rate and I'd also like to be able to take exposures in excess of 90 minutes. For these reasons, when Dick Greiner was selling off his equipment, I bought his GEG. What was my initial response as soon as I had the chance to experiment with it? I hated it. Then again, I'm very well aware that the only answer for very long exposure AP is going to be an OAG for *any* instrument, not just for an SCT. For that reason, I really wanted to develop expertise with this piece of equipment. In particular, I was committed to working very hard to see if I could develop the techniques to make the GEG work reliably with the 201XT. A reliable 201XT/GEG combination would make for a relatively inexpensive entry into AP for beginners and would be extremely reliable. Anyway, after sitting on the shelf for a while I've returned to working out the bugs with it.

I might add that I think I'm heading in the right direction here. My recent experiments indicate that it might really be possible to circumvent some of the weaknesses of the 201XT that make it problematic when coupled with an OAG. It'll be another month or two before I know for sure - I have to order a couple of parts from Lumicon this morning and it'll take me a while to expose a roll of film to see if I have the problems worked out. I'll report back to MAPUG when I have concrete results. I'm sure others must use the 201XT with OAGs and as I said before I find Guido's results extremely impressive (and Guido I *still* think you're very brave) but I'm trying to simplify the process to make it less intimidating for beginners.

Now Alan, if you're already successfully using an OAG with your LX200, don't look back. OAGs are harder to use and can be more expensive but if you're getting good results there's insufficient reason to go to a guidescope. Worse, with a focal length almost twice as long as what I've been using I'm not convinced a guidescope could be made to work with your 12". It would be an interesting experiment but considering your present success I would not deem it an experiment worth trying.

Secondly, I've written extensively on autoguider resolution with specific application to the 201XT. (Somewhere in the archives I've also included the appropriate pixel sizes and subpixel resolutions for the ST-4 and STV.) Check the Archives for the piece I wrote on guidescopes - that has some guidelines. In a nutshell, no matter what the focal length of your photographic instrument, if your autoguider can resolve at the 1 to 2 arcsecond level, you're guiding will be fine because the average seeing (particularly for a long exposure) will be unlikely to be any better than this. For the 201XT (with 10 micron square pixels), a focal length of approx. 2 M gives an angular resolution of 1 arcsecond. My guidescope actually gives 2.26 arcseconds per pixel with the 201XT and this seems to be adequate though I certainly wouldn't want to go to a shorter focal length. (Unlike the SBIG autoguiders, I don't know what the subpixel resolution of the 201XT is or even if it *has* subpixel resolution.)

Subject: Pictor Temperature Numbers?    

From: Ralph Pass <rppassrppass.com> Date: Oct 2001

Edward Registrato wrote:
> I am running Pictor ver 6.45. There are numbers at the bottom of the
> screen. Can anyone tell me what they mean?
> They read: 35.00, 41.00 93%
> a few mins later they read: 29.70, 41.50 100%
> a few mins later they read:19.60, 41.50 100%
> and a few mins later they read:12.40, 42.00 100%
> I would like to know what I am reading and could not find my book as a
> reference. I recognize there is some significance to these readings.

The first number is the sensed temperature of the CCD chip. The second is the sensed temperature of the case. Both are in degrees C. The last is the amount of power required to maintain the temperature. Getting to and staying at 100% is not good because the temperature is basically uncontrollable at that point.

The physics of the situation is that the heat removed from the CCD chip (to make it cold) must be dissipated. This will raise the case temperature. I have found that as long as you keep the power number less than 80% the system works fine. However, if after the initial cool down (where the power used is 100%) the power ever gets back above 80%, then the system becomes unstable, in that in trying to cool, it needs to dissipate more heat which raises the case temperature which means it needs to increase cooling power to dissipate more heat which raises the case temperature which..... until it gets to 100% power.

My rule of thumb is that when you first power up the unit and connect to it, the set temperature for the CCD should be no colder than 30 degrees C less than the initial case temperature.

Subject: 201XT Instruction Chart 

From: Rick Keil

My 201XT Instruction Chart, which you have in your MAPUG Topical Archive, has been reworked. I've added some additional helpful comments on callibrating and operating the 201XT. Below is the new reworked file:

DESCRIPTIONS OF SYMBOLS ON THIS CHART:

'/ '(slash) - EVERYTHING AFTER THE '/ ' (SLASH) IS WHAT THE PICTOR DISPLAY WILL READ.
'>'-automatically goes to
'S'-short press (less than 1 second)
'M'-medium press (1-2 seconds; the right side of the Pictor display will read '_')
'L'-long press (2+ seconds; the right side if the Pictor display will read '--')
'br-At' -star brightness at 'xy' ('x' being RA, 'y' being Dec)
'CA'- calibrating
'dr'- ready for darkframe
'df'- taking darkframe
'Er'- error (lost guide star)
'FF'- find/focus
'gb'- guide brightness (brightness of star being guided on. Minimum of 10-20)
'gc'- guide correction (correction that Pictor makes. 'gc' of '01' indicates Pictor made a correction of '0' in RA, and '1' in Dec. )
'gd'- ready to guide

NOTE!! - Once the Pictor 201XT has been calibrated properly, you can skip the calibration process (but only if you are photographing within roughly 30 degrees or so your last subject and using the same guiding configuration).

OPERATION

First locate guide star with an illum. ret. eyepiece (Meade 9mm illum. ret. is parfocal), and center the star. POWER ON >PI >FF* Let Pictor warm up for 15-20 minutes. Cover nose of Pictor M/drM/df>FF Insert Pictor, rotate the Pictor in the eyepiece port so RA is parallel with the longer physical dimension of the Pictor itself. S/br-At(center guidestar by using your keypad. If star is too bright or too dim you will need a different guidestar or you will need to change the exposure*** setting) S(to skip calibration process) or M/CA(to calibrate)(if Er is displayed then an error occurred. A S press will clear the error and return you to FF. You may need to enter different calibration times) >gd S/- - (blank to allow for shutter of your camera to open. Default setting is 5 seconds but can be changed. See 'SETTINGS') >gb/?? gc/??(xy axis)(if Pictor loses the star, then - - will be displayed. If gE (guiding error) displays, then Pictor quit guiding. M or L press will return you to FF) When done S, M, or L will return you to FF for next exposure.

* A long press at any time will access the FF prompt at any time.

** See 'CALIBRATING'

*** If the 'br' reading is too high (70+) or too low (00-10) then you'll need to cut or lengthen your exposure time until you get an adequate reading (ideal is around 20-50). To change see 'SETTINGS' below.

--------------------------------------------------(FOLD HERE)----------------------------------------------

y-axis (Dec)
0   CCD CHIP GRID
1
2
3
4
5
6
7
8
9
0 1 2 3 4 5 6 7 8 9
        x-axis (RA)

CALIBRATING

The correct calibration time for the Pictor must be figured in the 'br-At' mode. Our objective in figuring calibration times is to have the guidestar move 1/10th of the way across the chip. For example, a reading of '45' which has changed to '55' means the star has moved 1/10th of the way across the chip in RA. To do this, first center the star on the chip (a reading of '45', '54', or '55') in the 'br-At' mode. Then press your RA button(either E or W) for 1 second. Now see what the new readings are (let it cycle through a couple of readings). If you started at '55', and now your display reads '65', then 1 second is the correct RA Calibration setting. If '75' is displayed, then you moved the star 2/10ths of the way across the chip, so .5 second is the correct RA Calibration setting. If '55' is still displayed, then hold the RA button down for two seconds. Keep going until you get the RA digit to move up or down 1 unit. Do the same for Declination calculating. To change these values see 'SETTINGS' below.

CHANGING SETTINGS

M*- medium press where indicated will bring you to the next '*' on the page.

EXPOSURE-POWER ON >PI >FF L/Et S/??(length of exposure) (M*) S presses will vary exp. times from 0.1 to 25 sec. L stores new exp. time. >FF When changing exp. times, a new df must be taken.

DELAY TIME */dt S/??(length of delay time) (M*) S presses will vary times from 0.1 to 25 sec. L stores delay time. >FF

SEEING COMPENSATION */Sc S/? ('O' for steady seeing,'1' for unsteady seeing) S toggles between 0 and 1. (M*) L/FF

CALIBRATE RA AND DEC TIME See above 'CALIBRATING */Cr S/??(length of RA cal. time) S presses vary slew times from 0.1 to 25 sec. M(stores slewing time) >Cd S/??(length of Dec cal. time) S presses vary slew times from 0.1 to 25 sec. M or L/FF

FACTORY DEFAULTS to restore them allow 5 min for 201 to idle; cover nosepiece w/opaque cap; remove power and reapply; when PI appears, then apply short press; FI (factory initialization) >FF default values: Et- 2.0, dt- 5.0, Sc- 0(off), Cr- 2.0, Cd- 2.0

Subject: Pictor Autoguider Flow Chart     

From: Wes Erickson <twesleytwesley.com> Date: Oct 2002

The Autoguider Flow Chart for the 200-series Pictors (201XT, 208XT, 216XT) is accessed from:
   <http://www.twesley.com/~astro/pictor.htm>

The direct link to the gif file is:
   <http://www.twesley.com/~astro/pictor.gif>

Subject: 208XT Manual Correction--Shutting Down Camera in Standalone Mode  

From: Alan Voetsch <critter12952yahoo.com> Date: Jan 2003

I don't know who writes the manuals for Meade, but I hope to meet him someday. I'd love to know if the guy is even legally sane.

I bought a used 208 last year and have read all the PERTINENT information in the manual about using it in standalone mode. I use it for autoguiding without a laptop. The manual says nothing about a controlled thermal shutdown, or so I thought.

On page A-4 with a chart of the 'Pictor Mode Diagram' there is the following piece of information: "Controlled Shutdown when using the autoguider in standalone mode:

It is important to perform a controlled shutdown even when operating the Pictor XT in standalone mode. To enter shutdown mode, make a long press when the display reads "gd". The display will then read C9 or C8, and begin counting down to C0. It may start at a lower number if the temperature is cool outside. Wait until the display reaches C0 before unplugging the Pictor XT."

That explanation is wrong. During shutdown last night I found a long press just takes you to FF as the manual repeatedly states. You must enter a MEDIUM press to enter shutdown mode. But what really irritates me is the fact that this information is located in the appendix (with the flow chart) and NOT in the instruction area for standalone mode. It's incorrect and in the wrong place. I'm not surprised.

Subject: Pictor 208/216 for Using With Maxim for Autoguiding?  

From: Don Tabbutt <dontabbutt.com> Date: Feb 2003

-----Original Message-----
From: Alan Voetsch
Due to some excellent advice from Steve Lindsey, I'm looking into the
possibility of running autofocus routines, acquisition programs and
autoguiding with Maxim. This will allow for VISUAL guidestar monitoring
DURING an exposure. I consider this essential when taking 2-5 hour exposures.

I've contacted Doug George at Cyanogen and he concurs that this is
possible. Even with a 208XT. He does say it will be slow and recommends
a better camera, but one thing at a time.

What I'd like to know is if anyone out there is using this equipment
together and what kind of results you've gotten.
-----End of Original Message-----

I guess you know the 201 cannot be used with a computer, but the 208/216 can. I'll reply regarding those cameras.

I have used the 208XT with MaxIm DL/CCD as the guide camera many times. As you probably already know, the 208XT is superb as a stand-alone guider, but it also makes a lot of sense to use MaxIm DL/CCD to actually monitor the guiding as it proceeds.

When the 208XT is in PC mode, i.e. connected to MaxIm DL/CCD or any other program, it's guider relays are inoperative. That means you cannot use the cable that connects the camera to the LX200 CCD port for guide corrections. Instead, you must take an exposure, download that exposure to the computer, have MaxIm DL/CCD analyze that exposure for appropriate corrections, and then send those corrections to the LX200 through MaxIm DL/CCD's telescope interface (RS-232). Although MaxIm DL/CCD automates this sequence beautifully, it takes time...too much time. My experiments show that for a guide star bright enough to use the 208XT's shortest stand-alone exposure time, 0.1 seconds, in stand-alone mode it will apply corrections every second or so. With MaxIm DL/CCD at the same exposure, and on the same star, the fastest I've ever been able to get a complete cycle is about six seconds. Longer exposures will add to that.

So I use MaxIm DL/CCD to find, establish the exposure time, center, and focus the guide star on the 208XT, then switch the camera to stand-alone mode for calibration and guiding through the LX200's CCD port.

If you are thinking of a remote controlled setup, I strongly advise not using the 208/216 cameras not only because of the above, but also because you must manually cap the guide scope to take a dark frame, which is essential for dim guide stars.

The state of the market right now is pitiful for guiding cameras. The ST-4 is gone, the STV is woefully overpriced and already an incapable antique for virtually everything it does, and the Meade cameras have the above limitations. The best alternative I've found is the ST-237A which will work with the STV's eFinder, but it's $1,295 plus the eFinder. With the ST-7i selling for $1,295 right now, it would make an excellent imaging camera/guider, but not both at the same time. I've tried it as a guider and it is superb.

What we need is a 208XT with a mechanical shutter and guider relay capability in PC mode (that's only firmware, which Meade could implement tomorrow). USB would also be nice. But by then we're probably up to the ST-237's price range, which has a much larger chip.

Somebody needs to make a replacement for the ST-4, and the STV/208/216 aren't the answer.

Additionally you wrote:
   "That sounds tricky..."

Actually, using MaxIm DL/CCD is a godsend compared to finding and focusing the star in stand-alone mode. Just remember MaxIm's exposure setting and set the camera to that exposure when you put it in stand-alone mode for guiding.

You also wrote:
   "What is the eFinder and what does it do?"

The eFinder is a SBIG device that does a couple of things. It consists of a small 1.25" diameter reducer lens called the FR237 that can be used on the ST-5, ST-237A, and STV to reduce the field to something like f/3.8 on a native f/10 scope. Along with a short 1.25" spacer, it will produce about f/6. It screws onto the camera's 1.25" nosepiece, kind of like a filter. In eFinder mode, the kit includes a 4" extender tube that screws into the camera's T-threads. You then screw the little reducer lens onto the other end and screw the short spacer onto that as a "dew shield". The whole thing becomes a 100-mm f/4 "telescope". SBIG swears it guides beautifully, but I've never tried it. Alan Dyer said it did a great job with the STV he reviewed in S&T a couple of years ago.

Keep in mind that although the reducer lens works with all three cameras, the eFinder setup only works with the ST-237A and the STV. You can read all about it here:

   <http://www.sbig.com/sbwhtmls/online.htm> Click on Accessories, then on eFinder...

Subject: Meade 208/216 Autoguider.exe Software Link  

From: Dr. Michael Blaber <blabermailer.sb.fsu.edu> Date: Feb 2003

The Meade autoguider.exe software for the Pictor 208/216 can be found at:
   <http://www.meade.com/catalog/pictor/pictor200.html>

Venting Frustration with the 201xt   

Subject: Pictor 201 Killing Mother Board?  

From: Doc G, Date: Sep 2003

----- Original Message -----
From: Bostjan: I wrote to the group a couple of times in the past describing
multiple (4x) failures (and replacements) of my 16" LX200 main board.
I suspect the cause was the Pictor 201 autoguider. Following is what I noticed:

- I turn on the LX200, it boots and starts tracking w/LED Ampere-meter showing approx. 2A
- I plug the Pictor 201 in the LX200 front panel and nothing changes
- I plug the Pictor 201 it into the 12V power supply and the current drops to approx. 1A
- I unplug the 201 from the front panel and the current goes back to 2A
- the LX200 and the Pictor 201 are attached to the _SAME_ 12V power supply.

Does anybody know what could possibly cause the described Ampere-meter "dance"?
Could the Pictor be the cause of the main board failures?
----- End of Original Message -----

What you are seeing is most likely the shorting of the amp meter circuit in the scope by the connection of the Pictor ground to the power supply. The power supply for the scope is not connected to the metal parts of the scope, but rather to an internal looking resistor that allows measurement of the current internally. The metal parts of the scope are the circuit ground for the electronics in the scope.

Thus you have a circuit, not desired, due to the metal parts of the Pictor touching the scope metal parts. This was the result of a stupid way to get an amp meter in the circuit of the scope. As a result, the scope must be run from a separate power supply from the Pictor.

This has been a long term problem with the LX scopes which resulted from a circuit design short cut that's not normally found in correctly designed equipment.

----- Original Message -----
From: Bob White: Doc, could you not add a blocking diode on
the 201XT's power cord (ground side) to remove this ground loop?
----- End of Original Message -----

Unfortunately, you then also interrupt the power to the Pictor. Ops! A separate supply is the only solution unless you do not want to use the amp meter at all. Then you can short the ground of the power supply to the metal part of the scope base. This will work, but you will then not have the use of the amp meter. Since the amp meter is useless anyway, you might find this a good solution. I know many have done this.