Pictor 416/1616 Issues

       

Subject: Getting Started with the Pictor 416/1616- Setup and Focus    

From: Michael Hart

This is the first part of a series on the Pictor 416/1616 and 201XT "How To" I'm willing to write, providing there is adequate interest. I'm purposely avoiding the theoretical in favor of the practical approach. I realize some of you will have other advice, in fact, so do I! The idea is to flatten the Pictor learning curve rather than present a discourse of theory and ideas.

I have over 500 hours experience on the Pictor 416 on a highly modified and outfitted 12" LX200 designed to be transported from a permanent pier to remote sites for emulsion and CCD imaging. I have torn down the LX200, removed optics and have added circuits to the LX200 electronics to meet my imaging needs. Of close to 100, mostly private letters I've written in the last several months concerning the Pictor 416/1616, I have seen a lot of recurring questions. If anyone is interested, private E-mail me for information on my non-profit February 17 Astrophotography Imaging lecture.

If you have little to no experience with CCD imaging, avoid complicating things by buying a lot of accessories before you have experience to know exactly what accessories will fit your imaging needs. What I use is based on MY needs, experience, equipment and the results I desire. For example, I do not use a flip mirror, but many do and should. There are no wrong answers here.

Start out by setting up the Pictor as described in the manual. Meade does a pretty good job, here. Thread the Meade off-axis guider onto your scope. If you have a standard SCT focal reducer, go ahead and thread it on before the Meade guider. Add the Meade T-mount extension tube and 1-1/4" eyepiece adapter to your Meade off-axis guider. Add a barrel extension to your Meade 26 mm Meade Plossl and insert this into the guider about 1-3/4 mm PAST the end of the chrome eyepiece barrel. Focus on a rich star field. This will later put your Pictor in the focus ballpark. The 26mm is suggested here because you get one in that range with your scope and verifying your quarry later is easier.

Now, insert the Pictor. Orientate the Pictor the way you see it in the Sky & Telescope ads, NOT the latest Meade catalog. Power up the control box. The box will beep twice to indicate all is well so far. Launch PictorView. Open "camera", "preferences" and if your using a serial port, set the maximum baud rate to 57,600 for now. Click on OK. Close and open PictorView. By default, cooling is OFF, but that's OK for now.

In PictorView, click on the drop down menu and select manual focus. Now click on the "Edit Tool" (fourth icon from left). Set Exposure Time to 00:00:04 (4 seconds), Flat Field and Dark Field Time to NONE. Set Auto Focus OFF. Set Analog Binning ON. Set Pixel Resolution to 1X1 or 2X2 for faster screen updates (doesn't apply with SCSI). Anti-blooming, Color Filters and Mosaic should be OFF. Set Exposure Mode to CONTINUOUS. Click on "Save".

Now, click on the camera icon (first one) to start taking continuous exposures. Once the image is displayed, notice the bar at the bottom of the PictorView 2.0 window. As you move the pointer around in your image, notice the different pointer positions result in number changes in the 1|0:(x,y)=>a b area on the lower left side. x & y are the pixel coordinates and a & b are pixel brightness values in 8 and 16 bits per pixel or 256 and 65,536 brightness levels. The next box at the bottom tells the time, the next tells the Chip and Head temperature in degrees C. and the final box confirms a Serial or SCSI link.

Turn the focus knob counter-clockwise a quarter of a turn at a time and watch for converging stars. When you start getting close, reduce turns to 1/8 turn. For now, be satisfied that when the brightness level of a star you pick with your cursor peaks, you are very close to focus. Adding numbers or marks to the focus knob is a good idea to help you go back to that peak value as you will surely overshoot. To minimize effects of the backlash and mirror shift (common to a factory SCT), turn the focus knob clockwise 1/2 turn, then finish counter-clockwise back to the number or mark you noted as peak.

Now, remove your Pictor and insert your eyepiece into the holder. Try to reach focus by moving the eyepiece ONLY. Use the eyepiece extensions that came with your Pictor to add any necessary length. Once you have the eyepiece in focus, mark the insertion depth with a pencil. Now, install one of the eyepiece stop rings that came with your Pictor. You have created a parfocal eyepiece with your Pictor camera that will quickly get your camera in rough focus.

Focus can be refined further by more advanced methods, but YOU want to image something, anything.....hmm... the Ultramega Nebula is up...

Michael Hart, Husen Observatory

Subject: Getting Started With The Pictor 416/1616- Centering the Image  

From: Michael Hart

Considering the number of private responses I received from my first installment covering Setup and Focus of the Pictor 416/1616, I see there is sufficient interest to write the promised next installment, Centering the Image. For many of you that wrote me with interest about my February 17 Astrophotography lecture, I'm sorry that time constraints didn't allow timely replies. The lecture was well attended and featured (12) 8" X 10" Pictor 416 CCD images and (4) emulsion comparisons.

By this time, you have focused your Pictor reasonably well, you might do better, but you want to image something. M-42, the Orion Nebula may come to mind, but M-42 is really quite hard to get the image you expect because of the huge differences in brightness between the trapezium area and the fainter nebulosity. At this time of the year, I'd suggest M-1, the Crab Nebula which is bright and large enough to be seen in your finder scope.

Now is the time to align your finder scope with the Pictor. Slowly (to avoid spoiling focus) slew to an obvious bright star. In PictorView, select the setup "manual focus" from the drop down menu that you edited per the first installment, "Setup and Focus". Now, click on the camera icon (first one) to start continuous exposures. If you are using an LX200, press the center (CNTR) button on the keypad. Use very quick presses on the N & S to center your selected star in the image. Notice which way and how much the star moves in the image. If the star goes off the chip, you simply press the opposite key to recover. Do the same for the E & W keys and so forth until the star is centered in the image. Now, carefully adjust finder screws to center the star you picked UNDER the cross hairs. Without additional equipment, you will be able to center your quarry fairly well on the Pictor CCD chip USING ONLY YOUR FINDER SCOPE.

If you own a LX200, you may want to select "high precision pointing" at this time. For high precision pointing to work properly, you must carefully align the scope using a reticle eyepiece or de-focus your scope to center your alignment stars. Now, select M and 1 and press "Enter" until the LCD bars are displayed. Each LCD bar indicates 10 degrees of slew required. Press "GO TO" to start your slew. If it looks like the Pictor will slew into the scope, press on one of the N, S, E or W keys to suspend your slew. Press the "Mode" key on the LX200 hand control to complete the slew abort. If you didn't abort your slew, the LX200 will slew to a Mag 3 or brighter alignment star and will prompt you to center the star and press "Go To". With the LX200 hand control in the "CNTR" speed, center the alignment star UNDER the finder scope cross hairs. Now, check the continuous CCD exposure and tweak the centering on the chip. If the focus is off, NOW is the time to tweak focus using the methods outlined in the previous installment, Setup and Focus. If slewing changes focus frequently, consider reducing maximum slew speed to help. Now, press "ENTER" to complete your slew to M-1, the Crab Nebula.

You have successfully found and centered an object on your Pictor CCD chip. That object could have been visually invisible. But even with a 4 second exposure, you see evidence of the crab nebula. Your excited and wonder what camera settings are needed to get the great crab nebula CCD images you've seen in the magazines.

Michael Hart, Husen Observatory

Subject: Pictor 416XTE & SCSI Problems --part 1 of 3   

From: Don Tabbutt <dontabbutt.com> Date: March 2002

I gave up on SCSI. I have the Adaptec 1480, the latest ASPI drivers, etc., on a stable Win98SE 400MHz PII laptop. Here's the bottom line, according to Doug George of Cyanogen, makers of Maxim DL/CCD (my interpretation):

The Meade implementation of SCSI I, in the camera's firmware, is an old standard that is no longer supported by any current operating system or driver. Because of this, Meade's SCSI cannot tolerate or recognize any type of "wait state" (I'm not a programmer, but I think you get my gist). Modern multitasking operating systems are constantly sharing CPU load between various applications, hardware, and housekeeping, but the Meade SCSI implementation must have nearly 100% of the computer's time to operate correctly. Current SCSI II drivers won't give it that time, and send "waits", which SCSI I doesn't recognize. So if the system is doing virtually anything else at all, the Meade SCSI I system ignores the wait commands generated by SCSI II drivers, and crashes when it believes the SCSI bus has timed out.

In practical terms, autofocus will kill it, so will planetarium programs if they happen to refresh the screen during a download, or just about anything else running during a download. It is so incredibly unreliable that I wonder about the legality of selling it as a 32-bit SCSI system. Since caveat emptor is the current level of consumer protection in the software industry (read a license agreement lately?), I'm sure there isn't a damn thing we can do about it.

On a more optimistic note, with Maxim DL/CCD, it is utterly stable in serial mode. The speed disadvantage of serial vs. SCSI doesn't really bother me. Where speed is most important, as during focusing, the small subframes download within a couple of seconds of real-time. The binned mode timing is reasonable for target acquisition and centering, and the full-frame download time (under a minute) is definitely slow but really inconsequential after a multi-minute exposure. Maxim DL has done a great job of making this camera useable and versatile with a serial interface. Although expensive, Maxim DL/CCD has so many outstanding features beyond camera control that I would buy it regardless of which camera I had.

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Subject: Pictor 416XTE & SCSI Problems -- part 2    

From: Steve Glazener <segpyreng.net>

Don - Just a suggestion, but have you tried going into the Adaptec SCSI BIOS setup and setting the SCSI II interface setting to 8 bit (SCSI I)? I think I can see your issue, and I empathize. Sometimes ya gotta 'dumb down' the so-called 'smart' systems to whip 'em back in line :)... but you trade off systems interoperability.

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Subject: SCSI and 416XTE Problems -- part 3 of 3   

From: Steve Glazener <segpyreng.net> Date: Nov 2002

----Original Message-----
I am writing to you because I found your reply in MAPUG to a problem someone had with SCSI and Pictor 416 in March 2002. I would really appreciate any comments. You mentioned something about going into the Adaptec SCSI BIOS setup and setting the SCSI II interface setting to 8 bit (SCSI I).

Here is my problem: My serial connection works well with MaximDL and the 416XTE.

I decided to go for SCSI to accelerate image downloading to work together with MaximDL CCD. Recently I bought the Adaptec APA-1480 PCMCIA card for my laptop which runs with Windows 2000. I downloaded the latest driver package from Adaptec and hope that I have installed it correctly. They supply a test software which tells you that ASPI32.sys , etc. has been installed. The device manager for the card tells me the driver is aic78xx.sys and says that the card is working properly.

When I turn on the computer, the SCSI connection appears in the Meade control box. In addition, the Pictor 416 appears as a scanner as a device component of the device manager in Windows although there is no driver for the "scanner." I then start MaximDL CCD v. 2.11 and the camera connects, I turn on the cooler and it starts cooling but after a few seconds it seems to wait and the cooler does not respond anymore. I can take images but there seems to be a lot of 'waiting.'

I have also tested this with another laptop running on Windows XP with the same Adaptec card. There the problem is even worse: The cooler refuses to turn on and the camera exposes but does not download images to the computer. I then tried delay times in the CCD menu but this has no effect.
----End Original Message-----

I've received several messages identical to yours, and all relating to the Adaptec PCMCIA card for laptops. First let me state that the solution that I presented in the MAPUG list was only specific to the AHA-2940 PCI bus card in a desktop PC, running Win98 SE, and the setting I described is in the host SCSI BIOS setup, that is started by pressing <Ctrl>-A during the initial POST phase of the PC. It is in this utility that the interface may be set from 16-bit to 8-bit.

However, at the support site for Adaptec:
<http://www.adaptec.com/worldwide/support/suppdetail.html?sess=no&prodkey=APA-1480> you will find a document (in .pdf format) called "Setup and Installation of the APA-1480" which you can download. In pages 8-9 of the manual they show how to turn off the Ultra and Fast options of the card using the Hardware Manager under Windows. I would start by turning off both of these features of your card and see if that helps.

I can't and don't want to speak for the type of SCSI interface that the Pictor line of products provides, and hopefully the manufacturer provides this information in the documentation for their cameras. All I can say is, match the type of interface that the camera provides (8-bit, 16-bit, Ultra, Ultra-wide, Fast, etc.) to the type of interface that the card is set up for. That should ensure that you get the best performance out of the camera and your laptop.

Is there a communication problem or the wrong driver? (With serial connection, all is fine but slow...) I am attaching a (virus-checked) zip file on my SCSI Adaptec files because I do not know where to set it to SCSII.

Subject: Pictor 416XT + Laptop + SCSI Connection --part 1 of 2  

From: John Mahony <jmmahonyhotmail.com> Date: Apr 2003

From: Edward Registrato
>I am planning to take my Meade LX200 and 416XTE equipment to a dark sky
>location. I have my 416XTE connected SCSI to a desktop right now. I use
>MaxIm DL and Meade Pictor software to run everything.

>If I switch to a Dell laptop instead of the desktop what should I do to connect it SCSI?

Meade seems to be serious about clearing up SCSI problems with their CCDs now. They've added considerable detailed info on their website dealing with getting the SCSI hooked up and operating correctly. I believe it's available from the pictor software download page.

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Subject: Pictor 416XT + Laptop + SCSI Connection --part 2 of 2

From: Mike Fuller <mfuller1satx.rr.com>

To connect it to a laptop, you'll need the Adaptec 1480 Cardbus (32 bit) card, and your laptop will need to support the Cardbus interface (which most anymore do). I successfully used that setup for several years, without trouble, on Windows NT 4 and Windows 2000. You'll also need the ASPI drivers, but you should already have them on your desktop. Just make sure to install them on your laptop too, if you haven't already.

Subject: Pictor 416XTE SCSI & Maxim DL Problems --part 1 of 2  

From: John Mahony <jmmahonyyahoo.com> Date: Nov 2004

Dick Berg wrote:
> I have a 32-bit SCSI card in my laptop, so that's okay. I still
> have to cancel out of the automatic XP plug-n-play hardware handler.
> The Meade hand controller shows v3.11 when I turn on the telescope.

You mean the scope's keypad? That has nothing to do with the camera. The last scope firmware version was 3.34, but you'd need to send the whole scope in to Meade to get it updated. 3.11 is the latest flash upgrade for the camera.

> The Pictor control box shows v1.2 when I turn _it_ on. I will flash
> the PROM anyway, as you say, just to make sure. I'm not sure if this
> will update the Pictor PROM though, but I'll find out!
> I continue to have relatively infrequent but annoying problems
> with the camera downloading interface to Maxim DL/CCD software, that
> adding pre- or post-exposure delays does not fix. The result is a
> (Maxim) camera error 401, and it requires me to shut down and
> restart the camera. I was just trying to think about some of the
> possible solutions that I could apply to get rid of this little quirk.

There is much info available from the Pictorview download page that will help diagnose SCSI problems. The latest Pictorview software v. 7.25 will check your computer to make sure you have the latest drivers from adaptec. That cleared up a lot of SCSI problems with my 416XTE. I had also tried Maxim and had mixed results and crashes until I got the SCSI straightened out.

But now I also have to cancel out of the "windows has found new hardware" window in win98 every time I start up the computer with the 416 powered up.

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Subject: Pictor 416XTE SCSI & Maxim DL Problems --part 2 of 2

From: Ralph Pass <rppassrppass.com>

I need to cancel the 'found new hardware window' too and it is reassuring to have the computer tell me that it can see the camera properly (sometimes I don't get the message and the Pictor Camera was not properly installed). However, once I do cancel out of the 'found new hardware window' I never have a problem using the camera or running the software (but I do use Pictorview Software).

Power up the Pictor. After the beep, go to the Pictor base unit. Press the down arrow key twice to get to Version Info and then press the enter key. The top line shows you the firmware version (latest is 3.11). The second line shows the version for other software (I think the load software in the box). This is BV1.2 and is from October 1994.

Subject: Pictorview 7.14 & SCSI Advice  

From: David Eyer Date: June 2002

I use PictorView 7.14 with a 416XT camera (firmware updated) and a 2940 Adaptec SCSI card on Win98SE. The setup works reliably now but it did not work at all when I first started. *I suggest starting with the bare minimum setup to reduce the number of potential things going wrong. Many times a seemingly complex problem is really just more-than-one simple thing going wrong. *Avoid connecting other devices to the SCSI cable when using the Pictor, at least until you're past the errors. *Disable serial connection options in Pictor USER PREFERENCES(7.14)until you get rid of the errors. *Make sure all your physical connections are good (no bent pins) and avoid connecting short cables together to make a long one.

A good SCSI cable is very important and it should be kept as short as possible. I suggest less than 10' until the errors go away. I use 25' now between my PC and observatory.

There is a driver called STIMON that comes with some imaging program (I forgot which one). It can cause communication problems. Use <ctrl-alt-del> to display running programs and terminate this one if you see it running. If you find it running, you can disable it permanently using the MSCONFIG program to un-check it so it doesn't load at all.

I tried MaxIm, it didn't help until the SCSI and COM problems were corrected. You can try the demo to help troubleshoot. If it still fails using the MaxIm demo, then focus on getting a simple configuration to work. After that, it's easy to change one thing at a time to suit your needs. Just make sure you test after each change to make sure it still works. Consider upgrading to WindowsME, it does a much better job of managing memory and devices.

Subject: SCSI to USB Converter to Connect the Pictor? --part 1 of 2 

From: Bob Parry <robpartelus.net> Date: Dec 2002

Taylor wrote: Is it possible to use a SCSI to USB converter to connect the Pictor SCSI port to a laptop with only USB ports. I am trying to remote my LX200 by 20' to be able to work indoors. I am running Windows XP and would like to get something a bit faster than a serial connection. The CCD is a Pictor 416XT and I have the latest Maxim DL and pictor software. The SCSI converter is a Adeptec USB2Xchange with a SCSI1 to SCSI2 adapter and an active USB cable 20' long. I have read the scary accounts of trying to get the Pictor to work in SCSI mode and would like to do it without a second computer. Also, not being a computer expert I am wary about doing something wrong and frying the works! The Adaptec converter has driver software.-------end of quote--------

I had a similar problem with my laptop, no serial ports, and a 416 XT camera. I looked into one of those SCSI to USB converters but as they were extremely new at the time (about 2 years ago) I went a different route.

The implementation of the SCSI protocol for the Meade cameras I have been told was not done by Meade but an outside supplier who basically wrote to one device and not the SCSI standard, which is why they are rather "difficult".

So I purchased a Serial to USB converter and an Adaptec 1480 SCSI card to work with my IBM laptop operating under Win 2000. This has been very dependable and I run an LX-200 through Earth Centred Universe and Maxim/DL to control the camera. I have had no problems running both of these programs at the same time on the laptop. ECU runs through the serial connection and the 416XT through the SCSI. I have also checked that it will run completely serially which it does fine with ECU and Maxim/DL, but interestingly enough Pictor would not connect faster than 9600 through the USB-Serial convertor.

I timed the download times to compare between serial (115,000) and SCSI. The serial connection at full resolution took 60s. The SCSI connection took 18s to do the A-D conversion and then 3 maybe 4 seconds to download. So SCSI is about 3 times faster from frame closed to image on the screen. Most of the time is spent doing the A-D conversion.

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Subject: SCSI to USB Converter to Connect the Pictor? --part 2 of 2

From: Bruce Gillespie <Brucepcb.co.za>

Being in the IT business and a PC veteran, perhaps I can throw in my 2 cents here ..

USB is very hassle free generally and it's almost impossible to fry the PC, you can't go wrong with USB. I took a look at the spec sheet for the Adaptec adapter, its supports USB 2 which is a higher speed version on the former which might make a difference in terms of downloads if your notebook supports that. Its Auto-terminating so you won't have to hassle with that on the PC side of the SCSI Cable so the only thing to setup is the SCSI address (very simple each device must have its own address) and you will have to setup the Pictor as well in this regard (sorry I don't know this product). Adaptec generally make good products, I have had a Adaptec PCMCIA SCSI Adapter for years with no problems.

I also had big ideas about running two laptops on site, one for tracking and controlling the scope (with The Sky) and the other for video frame capture and display from my StellaCam but it really turned out to be a hassle - dealing with one Windoze PC is one too many! And then there is a power requirements in you are in the field as well to worry about. And desktop real estate. Try get it set on one unit if you can - W2000/XP is half decent at multitasking (relative to earlier versions that is) - make sure you have at least 256MB RAM though.

Subject: RA & Dec Calibration Times of Meade Guiders

From: Alan Voetsch <critter12952yahoo.com> Date: Nov 2002

I've been playing around with the user-set RA and Dec calibration times on my 208XT. I'm positive these results would also apply to the 201XT, and most likely to the 216XT (but I've never used the 216).

The manual instructs us to enter the times in the following manner; in the find and focus mode, count how long (using guide speed) it takes to move the star 1/10th (or one unit) of the way across the chip. This is the number (in seconds) that we're supposed to enter for each axis. My experience has shown that these numbers usually work out to '2' for RA, and '1' or '2' for declination. I've used the 201 for 3 years on both a 10" and 12" LX200, now I am using the 208 on the 12". My guiding results have never been a whole lot better than mediocre.

Ralph suggested starting the calibration procedure from one of the corners, instead of the center, and using larger numbers in place of the '1's and '2s'. Last month, I tried this out and consistently ended up with the star off the chip, otherwise known as 'Er'. I finally settled on '3' for RA and '2' for dec. The roll of film I shot after that was a major improvement, but still not perfect. Tried again tonight, and I believe I got it as good as it's going to get.

Starting from the '9' and '0' location, using time values of '6' for RA, and '5' for dec, I was finally able to get the 208 to run through a complete calibration, keep the star on the chip, and still end up fairly close to center. 7 was too much in RA, and 6 was too much in dec on my 12" LX200 at prime focus with a Taurus Tracker III. Apparently, the longer travel times increase the sensitivity, and accuracy of the guiding corrections.

Subject: Pictor 416: Pin-out of Guider     

From: Jack Wikoff

Pictor Ctrl Box Guider(CCD)

Pin 1 - +5V

Pin 2 - Grd

Pin 3 - Left

Pin 4 - Down

Pin 5 - Up

Pin 6 - Right

201XT CCD Conn. Pinout

Pin 1 - Right

Pin 2 - Up

Pin 3 - Down

Pin 4 - Left

Pin 5 - Grd

Pin 6 - +5V

Subject: Pictor 416/1616 Control Box Description    

From: Michael Hart

The Pictor 416/1616 Control Box buttons were primarily designed to be used with a 505 Video Card Connector and Floppy Disc Drive. One could perform motion calibration, autofocus, set exposure times and take images with only an inexpensive 12 VDC B&W TV for a monitor. In this way, no computer was needed. The arrow keys are used to access different modes, the enter key activates a selection, the cancel key cancels a selection and number keys (1,2,3,4,5,6,7,8,9 & 0) are used to enter a value. The display provides useful information such as exposure times used in motion calibration and star position as well as manual settings that saturated the detector resulting in a warning: "too bright". The star x,y positions give feedback in motion calibration, for example, the progress or lack of progress.

The 505 Video Card Connector and Floppy Disc Drive was never made available to the public to my knowledge and most of the user accessible control box keypad functions were duplicated with software control in the final version of PictorView 2.0. PictorView XT 6.X did drop software control of motion calibration, so the control box would be used for that function. I suspect that motion calibration will eventually be included in PictorView XT 6.X.

The control box serves as a distribution box and power supply for the camera head as well. In this way, only one wire is needed for the camera head and 12 VDC can be applied directly without an additional external power supply and inverter. The jack labeled LX200 is connected to the jack labeled RS-232 on a LX200 to allow auto-centering, auto-mosaic and auto-focus, which I have used. The jack labeled RS-232 is connected to the serial port of a your computer via an the RJ12-DB9 adapter and phone cable, if computer SCSI support is not available or desired (such as when upgrading the Pictor flash BIOS). The jack labeled CCD is used to connect the Pictor 416/1616 to non LX200 scopes with standard normally open guider switches using the phone cable with blue shrink tubing end plugged into the telescope. The plug labeled SCSI is for connection to a SCSI adapter on your computer to enable high speed image transfers.

Not related to the control box is the 201XT autoguider, which is plugged into the CCD port of a LX200 or non LX200 using the coiled phone cable.

This covers all current user accessible functions of the Pictor 416/1616 control box buttons and jacks accessed and described by PictorView 2.0 and PictorView XT 6.X camera control software.

Subject: Pictor 416 Warm-up  

From: Michael Hart

In my discussions with Kodak engineers, I did specifically ask about warm-up. They assured me many imaging applications with this chip using TEC cooling similar to the ST-7 and 416 did not require special warm-up or cool-down procedures to prevent chip damage. More specifically, I was assured the Kodak 0400/1600 could handle the TEC heat dump from sudden power removal.

The KAF-0400 chip used in both the ST-7 and 416 is very robust and are quite capable of very fast cool-down OR warm-up with no permanent effects to the imaging capabilities of the chip. There may be some stability issues with respect to the data obtained from a chip running at very low temperatures and of course, increased thermal noise at warmer temperatures.

I believe the limiting factor in the ST-7 is the not the KAF-0400/1600 imaging chip but rather the TC-411 guiding chip that IS sensitive to sudden temperature swings. As the Pictor 416/1616 use only the Kodak chips, cool-down or warm-up from the TEC does not apply to these cameras. I have way over 2000 hours on my 416 where no special warm-up procedures are used-- I just pull the plug. This agrees with Meade's recommendations and specific exclusion of a warm-up algorithm in PV 6.X software for cameras using the Kodak 0400/1600 chip.

Just in case Kodak has changed their recommendations, I spoke to my Kodak engineering contacts this very day to make certain. My discussions with them may result in specifications that directly address this issue.

Subject: 416XT with Taurus Tracker III     

From: Michael Conte <mcontecrosslink.net>

Dave Feldstein wrote:

> In your last reply you stated after you focus the object with the 9mm you fine tune it for the camera. Is this with the main focus knob or adjusting the camera in and out of the tube<

No problem Dave, since I don't know if you're currently using a tracker at this time or not, I'll assume from your message that you are and try to explain how I do it (much easier then it'll sound).

1. Attach the CCD camera to my SCT (actually, it stays attached most of the time).

2. Insert the 9mm guiding eyepiece.

3. Find bright star.

4. Focus telescope through eyepiece using main focus knob.

5. Flip the mirror and take a short exposure ( 1/20 - 1/10 second).

6. Normally, the image is nearly focused, but then I fine tune the focus using the main focus knob and repeat step 5 until I'm satisfied with the focus.

7. Flip the mirror down and check the focus in the guiding eyepiece. If it's not quite right, I adjust the

focus using only the helical focus of the eyepiece (not the telescope).

7. Flip mirror back up and go looking for whatever I want to image that night.

8. Center whatever it is I'm going to photograph in the guiding eyepiece, flip the mirror back up and take

about a 30 second exposure to make sure it's centered, then I'm off and running.

The whole process takes about 5 minutes

> Tried imaging again last night,
> first tried M15, got star field and edge of it, never could center it on chip.

Sounds familiar!

> Then tried the moon, got bright spherical image no definition,

With my setup, I can't take an exposure of the moon unless I REALLY stop the scope down (like to 2") or use

a high neutral density filter. It's just TOO bright!

> Put 26mm lens in area of prime focus end of my OAG, used knob to bring to
> focus and centered image. Removed 26mm and inserted camera.In the case
> of saturn got the ring image(not saturn) a defocused image. Did the
> scotch tape trick moved tube in and out and got brighest image, but
> unrecognizable as saturn. Retook shot with camera using stop ring as set
> with scotch tape same results. Where am I going wrong?

If you're not using the Tracker (or equivalent), it sounds like you're trying to image the same way I tried for awhile. Find object, focus using eyepiece, insert camera, guess at focus, take picture. Some of the problems I found was that attaching the camera to the scope cause enough flexure to move the object off the chip. Using this method, about the only way I had any success was to find a bright star, take bunches of photos adjusting the focus each time until it was good, remove the camera, insert an eyepiece and see what it looked like.

I removed the lens from my barlow to use it as an extension, put the medium power eyepiece in, slide the barlow in back and forth until I found a good focus, locked the tube in place and mark the barrel with tape or something to show how far to slide the tube in to get some where near the focus point for the camera. It'll work in a fashion, but it's not the best way to do it!

Subject: Supplementary Fan Cooling of the Pictor 416/1616     

From: Michael Hart

I have done some rather extensive work with the Pictor 416 TEC and internally with my ST-7 TEC system. The TEC stack in a 416 generally works best with a bit of air movement over the fins. Only a VERY SMALL amount of air is needed as the surface area of the fins is adequate for the rated delta-t of 40 degrees C. to air. Indoors, it is not unusual for the air to be quite still, slowing typical convection currents. When his happens, the camera's internal temperature will rise with the external temperature, possibly causing an Overheat Warning.

On the scope, my 416 has always has adequate circulation unaided due to natural convection and infrared black body radiation to the cooler surroundings. There may be certain ambient conditions for some that may cause the camera head to produce more heat than can be dissipated to surrounding air.

If the TEC setpoint is quite low, this can result in a "Overheat... beginning cool down" warning display on the camera control box. Rebooting the camera will clear it, but the cause is quite often room air temperatures and/or inadequate air circulation. I use a very small slow speed fan powered by the 416 internal electronics mounted across the 416 fins. This assures forced convection that results in about 43 degrees C. delta-t in still air. More air flow results in little to no improvement in the delta-t. Most can easily power the fan with external 12 VDC power.

Many small fans produce vibrations that can be transmitted to the image when direct mounted. Careful fan selection, testing and mounting is important if a supplementary fan is used. Computer style fans are usually designed for large air flow and have fairly strong permanent magnets with aggressive fan blades. Even if you slow them down to just above stall speed with a dropping resistor, residual cogging and fan blade shape can generate enough vibrations to effect exposures.

I believe you will find there are many brands, speeds and fan blade designs available. On my 416, I'm using a ball bearing, 7 blade medium pitch, slow speed, 1-9/16" square AOC brand CPU cooling fan. It is over 3 years old- I don't recall where I bought it. With further speed reduction, it is difficult to hear and produced no vibrations effecting the image.

Look for fans designed for low volume applications, such as SOME CPU cooler fans. For example, the Radio Shack #273-246 1-9/16" fan with heat sink is a 486 CPU cooler fan, but is unsuitable at rated voltage- it sounds like a tiny turbine, has sleeve bearings, and an aggressive 8 blade pitch that vibrates. At close to stall speeds, it MAY work.

The larger 2" Radio Shack #273-247 486 CPU fan with heat sink (remove heat sink) is much slower at the rated voltage and responds well to a dropping resistor. It still has a rather aggressive 8 blade fan, but appears to be a good candidate, especially with a dropping resistor.

Whatever fan is selected, use a voltage dropping resistor to further reduce the speed as needed to something above stall speed or a bit faster- the voltage needed to self-start the fan. Something in the order of 150 ohms placed in series with one power lead should be a good start, depending on the fan selected and speed desired.

------------------------------------------------------

The GIF shows the relative locations for the head cable clips. The illustration also shows the location of a small 1-9/16" cooling fan. Both have been in use over 3 years. The small fan prevents overheating during low air flows such as indoor testing. I cover proper selection and use of supplementary cooling under the subject: Supplementary Fan Cooling of the Pictor 416/1616.

Early Pictor 416/1616 CCD cameras made no reference to avoiding head cable disconnection while the control box is powered up. Later, Meade felt the camera's electronics could be damaged if the head cable was removed while powered up and so advised in subsequent user manuals.

I allowed cable removal to avoid pulling the control box and possibly my laptop during a slew. Since Meade now advises against head cable removal, I added cable clamps which allow no tools cable attachment, even during sub-zero weather. In spite of many head disconnects without any problems, I decided to add the clips to assure that the head cable could not disconnect.

---------------------------------------------------------------------------------------

Hardware store parts needed:

(2) #3304S Serva-Lite 1/4" X 3/4" wide nylon cable clamps

(2) 3-48 X 1/4" stainless machine screw

(2) 3-48 stainless machine screw nuts

(2) #2 stainless flat washers

(1) 3/32" drill bit

      Locktite medium strength thread locking compound.

-----------------------------------------------------------------------------------------

Similar clamps made out of polyethylene or polypropylene are not suitable. If the clamp doesn't spring back, it's not nylon. I used stainless steel screws, but brass or steel are fine.

Mark the locations for the cable clips as shown in the attached picture. You may want to drill more to the outside of the camera to avoid drilling into the sealed camera case. Use a 3/32" drill to make your holes. Next, drill the nylon cable clamps just inside the molded mounting hole. I slightly enlarged the cable clamp with an Exacto knife and a #11 surgical blade (standard Exacto blade) to enable insertion of a screwdriver for tightening.

Install the #2 washer onto the screw and into the cable clamp.

Insert the assembly through the clamp. Add Locktite to the threads. Next, turn the camera over and slide the nut into the cooling fin. Using a jewelers screwdriver or similar object, start the nut on the screw. You may want to slightly pull the screw out to enable starting the nut. Use the jewelers screwdriver to jam the nut while using another small jewelers screwdriver to tighten the screw.

To install the head cable, simply spread the clips with your fingers and insert the cable. Next, plug the cable into the Pictor camera. Reverse this procedure to remove the head cable.

---------------------------------------------------------------------------------------------

It is possible that by the time the first temperature readout is updated, the chip temperature can be close to 0 degrees C. Subsequent updates are every two seconds, but other functions with higher priority (such as downloads) will delay temperature updates. The % number represents the percent of cooling capacity used and is really a conversion from the maximum voltage applied to the TEC.

The first number represents the measured temperature of the cold finger quite near the chip itself and is used to indirectly indicate chip temperature. The number in the middle (if still used) represents ambient temperature as measured inside the camera. It is/was also used indirectly to calculate a setpoint for max cooling. I use the is/was statement to indicate I don't know if these features are fully working or retained in the latest beta versions. This ambient readout may be only available in the 416/1616 cameras, I don't know. It was added at my request by Meade in PV 6.X software.

In this way, one can gauge the ability of the cooling system to dissipate heat and run the system quite close to the rated 40 degrees C. delta-t. The max temperature setting varies the ultimate setpoint depending on the ambient reading and is not a suitable setting for dark frame libraries. Using the maximum temperature setting does not mean the cooling system runs at 100% all the time, rather, the cooling system setpoint is calculated for the coldest setting that can be sustained by the ambient temperature.

Arguably more important, the ambient readout can be used to better match library dark frames, especially important in CCD cameras that more readily couple some of the ambient to the CCD chip. In this case, having different ambient temperatures produces different results at the same chip temperature as parts of the chip are really warmer/cooler than the chip temperature indicates.

Subject: Cleaning the 416XT Article Link   

From: Chris Heapy <Chrisheasynet.co.uk>

I've finished posting my article on dismembering a 416XT, and it's now back in one piece. Cleaned the inside (removed an irritating spot on the chip itself which showed on all my images). Interesting sort of job if a bit fiddly at times.

Article is at: <http://easyweb.easynet.co.uk/~chrish/lx_416i.htm>
Note: should open new window over this one.

Subject: 416XT RGB Exposures  

From: Michael Hart

R. A. Greiner wrote:

> Bob Freeze wrote:

> > Well, I finally received my filters and adapters. While waiting for

> > clear sky I decided to see if I could figure the proper exposure

> > ratios for my particular camera/filter combination.

> > In order to figure this out, I set the 416XT up in the darkroom so I

> > could use the enlarger as a light source. BIG ASSUMPTION -- the

> > enlarger produces light equally across the visual spectrum. I think

> > this is true because I have zero enlarger color factors when doing

> > color prints.

> > Anyway, I found that the following exposures produced equal pixel

> > values:

> > RED (25) = 1

> > GRN (56) = 1.62 (yes, I know that 58 is the standard GRN for this set)

> > BLU (47) = 3.5

>>

> > With a RED exposure of 1 second (and GRN/BLU set accordingly), I had

> > peak values in the same part of the image of 47,000 as reported by

> > PVXT 6.4.

> > If this is accurate, I'll be looking at just over an hour for a set

> > with a 10 minute RED exposure!! --Bob

>

> This is very interesting and solid data which I believe to be correct.

> There is one major issue you need to take into account. The color

> temperature of the enlarger bulb is probably about 2800 to 3200 Kelvin.

> The color of a star is more like 5800 to 6000 Kelvin. Thus the star

> which you might like to have look normal (neutral or white) will have

> much more blue in it than the enlarger light...

>

> I would expect your exposures to be somewhat more balanced in time than

> you anticipate from your data. Never-the-less, the blue exposures are

> always rather long because of the low sensitivity of the chip to blue light.

>

> There is some rather detailed discussion of these issues on my web site

> under. Attachments/Filters which you might find interesting.

> Doc G

-------------------------------------

Doc G is correct about the desired color temperature needed to best calibrate RGB filters. The 5800 to 6000 K corresponds roughly to a G-2 type star positioned with minimal atmospheric attenuation of the shorter blue and to a lessor extent, the green wavelengths. Why 5800 degrees K? Because this corresponds to the effective temperature of the sun (5770 degrees K., spectral type G2) which the human uses to see color.

Why bother with calibrating color filters if one can adjust the color balance in the software? Because achieving relatively balanced exposures also balances the S/N ratio of each channel. As a result, greater color saturations (and more) may be considered due to the minimized noise. With stacked images (shift and combine or track and accumulate), poor calibration times may result in unexpected colors.

There are relatively few bright G2 stars brighter than Mag 3 (only three come to mind) I believe the best and easiest way to calibrate a selected filter set with a particular CCD camera is to use the sun itself. I use a full moon quite high and a neutral gray test card, a camera store item. John Hoot has suggested a way that may be simpler-- image the moon directly. However, I would suggest stopping down the telescope, if needed, rather than using a neutral density filter which may not really attenuate all wavelengths equally.

Are exact ratios critical? No, because atmospheric attenuation that varies with altitude and atmosphere conditions will cause the ratios to vary quite a bit. If you expect to image quite low, wait until the moon is near the altitude you will be imaging and calibrate your filter set. Don't forget to use an IR filter with Wratten and dicroic filters to assure IR leakage doesn't skew your results.

How can one determine the initial ratio? Start out by comparing the CCD chip's QE (quantum efficiency) in the center of the wavelengths passed by your filter set. With Kodak 0400/1600 chips, a filter set that results in surprisingly low blue exposures is likely leaking light from non-blue sources such as infrared and green and possibly the red channels.

Subject: Continuous Frames with Pictor 416XTE--part 1 of 2 

From: Douglas Benn Date: May 2001

Once again the Meade manual leaves me mystified.

I would like to take a series of frames with the minimum delay between images. I have a 416 with a SCSI interface in Windows 98 system.

The manual says you can take up to 50 images continuously with the settings unchanged. However, I assume there will be an inevitable delay of several seconds while the chip is read out. As I will be looking to make photometric measurements from only 3 stars in the image can I reduce the readout delay: 1. By defining 3 small regions to be read out only? 2. I have Maxim DL. Is there a software routine to do this either in PictorView or Maxim DL i.e. define local regions to be downloaded? 3. If this is possible, how long will the intervals be between successive image captures?

---------------------------------

Subject: Continuous Frames with Pictor 416XTE --part 2 of 2

From: Douglas George <dgeorgecyanogen.com>

Douglas, you can specify a subframe region in MaxIm DL, but only one at a time through the user interface.

However, you can write a simple VB Script which will sequence MaxIm DL images with different subframes, and save them to disk. That will do exactly what you want. Have a look at the Scripting section in the on-line help or manual.

The delay between images depends on the time required for camera readout and download. The smaller you can make the subframe the better.

With Pictorview you can draw a box (and only one box) in the image and have that be the subframe returned. Pictorview also allows you to use a full frame dark and flat image and will automatically extract the subframe that matches the subframe of the image you took.

Subject: Pictor 416XT Icing Fix -- part 1 of 2    

From: Chris Heapy <Chrisheasynet.co.uk>

Some 9 months after making the mod to my 416XT adding a removable desiccant cartridge it's starting to ice up again. I guess it barely made it through one of the wettest winters I can remember but I still expected it to last a bit longer than that. I think there must be a leak somewhere but I can't imagine where it might be.

Still, it's only a 20-30 min. job to replace the desiccant so that's not too bad. While I had it apart though I added 2 gas nipples so it could be purged with dry gas after re-assembly. I've expanded the article below to include this procedure.

<http://easyweb.easynet.co.uk/~chrish/lx_416i.htm>
  Note: should open a new browser window over this one.

------------------------------------------------------------------

Subject: Pictor 416XTE Icing Fix -- part 2 of 2    

From: Geoff Todd

I think I fixed the icing problem in my 416XTE. The symptoms were variously, multiple additional "stars" in the images, or areas of frost visible in the images. When I opened the camera the cause was obvious - the o-ring seal was not in the seating groove all the way round, and had been pinched inside the case for a bit less than an inch, leaving an air path into the camera. It must have happened when the camera was last sent to Meade for shutter repair, about 7 months ago. The silica gel had worked hard but finally became saturated. Chris Heapy's guidelines were invaluable in outlining the process of getting the circuit board out and back. I reused the same silica gel bags after reactivation. The camera has been back together and working for a week and a half so at least the operation was not fatal. Time will tell whether it is a long term fix for the icing.

I learned some things that might be useful to others with this problem:

- It helps to study the pictures of the opened camera that are published on Chris's site,
   <http://easyweb.easynet.co.uk/~chrish/lx_416i.htm>
  so that time is not wasted once the camera is opened and vulnerable to internal mechanical damage.

- Choose a workplace which is clear of distractions, dust and breezes.

- Heating the silica gel bags to 150C is probably too hot as the bags went a bit brown. 120C might be a better choice. I cooked the bags for over 3 hours and this seems to have driven off the water.

- It is worth vacuuming out the camera case while it is open - I found some bits of stuff inside that were better out than in and explained the occasional strange blob on my images. The stuff must have been moving around inside. Vacuuming is better than blowing as you know the stuff has not been moved somewhere else inside.

- The top of the CCD is unencapsulated with exposed bond wires onto the chip so be extra careful near it. I vacuumed around it but not directly on it.

- I did not need to unstick the case temperature sensor as with care it was possible to tilt the PCB up enough to get the bags out and back with it in place. In my camera at least ther is enough slack in the connecting wires.

- My camera has PCB locating threaded studs which are not there in the Heapy pictures. These make it relatively simple to get registration with the header socket under the board when the PCB is replaced. The studs are presumably a later enhancement (my camera is 3 years old).

- The o-ring in its rest state is smaller in diameter than the recessed seat in the camera body in which it has to sit. I VERY CAREFULLY stretched it to a larger size by hand then placed it into the seat. It takes about 15 to 20 seconds or so to shrink back to its original size. In that time it

must be placed in the groove, the shutter cable plugged in, and the camera front (with shutter) fitted over the o-ring and secured with the countersunk socket screws. You can check whether it is seated properly by looking into the gap between the camera front and body in a good light - I used sunlight. Rotate the body slowly and the o-ring should be just visible at a constant distance from the camera circumference. If there is a gap the o-ring has jumped out of its seat at that point and the front must come off so it can be restretched and reseated. Mine was OK on the second go.

All in all an interesting exercise and one I am not in a hurry to repeat, but at least I know I can if I have to.

Subject: Focusing the 416

From: Ralph Pass <rppassrppass.com> Date: March, 2000

My technique for focusing (and imaging) is as follows:

1. I set the fast slew speed of my LX200 to 2 degrees per second (just to avoid any chance of mirror whiplash as I move from the focus star to the object).
2. I use the 'goto to nearest star' option of the LX200 menu to get to a bright star near the object of interest.
3. I put a Hartmann mask on (two or three holes) and pick an exposure of 0.5 seconds
4. After taking the first image, I adjust the image scale so the range is about 30000.
5. I then select the rectangle icon and draw a reasonable box around the star
6. I select 0 delay (since I am using an electric focuser).
7. Once the star is centered and looks sharp, I start cutting the frame size in half until the FWHM graph appears. I use the halve exposure to get the max value to around 30000.
8. I gently tweak the focus allowing several images to go by before the next image tweak.
9. Where I am I find the brightness and the FWHM bounce around a fair bit (which I attribute to seeing). I want the FWHM to reach a low value twice before tweaking the focus.
10. There is a good, but not perfect, correlation to brightness and FWHM.
11. Once the FWHM looks stabilized, I call it focused and remove the Hartmann mask.
12. I then slew to the object (Pictorview has remembered it for me. Senior moments might lead me to wonder why I was pointed in the area!).
13. I compose the image with 15 second, binned exposures.
14. I then find a guide star (201 attached to an ETX which is piggybacked)
15. I shoot many images. My preference is 5 to 10, eight minute exposures. I really want good S/N.

You can see the fruits of my labors at my web site:

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

Since the focus images are not saved (and there is no option to save them), I cannot provide direct views of what I see. Perhaps the next time I am out I can grab some screen shots and post them to my web page.

Subject: Cooling the 416XT CCD Camera   

From: Chris Heaply, July, 1998

I've added some information on cooling the 416XT CCD camera to the end of the de-icing article at the URL below:

<http://easyweb.easynet.co.uk/~chrish/lx_416i.htm>
Note: should open a new browser window over this one.

There are graphs which illustrate cooling vs. time, and also the effect of adding a small fan (in still air conditions).

Subject: Pictor 416XT Liquid Cooling? 

From: Michael Cook <michaeljcookrogers.com> Date: May 2001

SOates4616aol.com wrote:
> Has anybody done any experimentation with adding some type of liquid cooling
> assist to a 416XT camera? Living here in the desert of Nevada, night temps
> remain above 80 degrees F most of the summer. It becomes difficult to get a
> camera temp to stabilize much below +5 C. I have installed a cooling fan
> which has helped, but it still doesn't enable the temperatures I'd like. Any
> input on this subject would be greatly appreciated.

I will be experimenting with liquid cooling for my 216XT. I'm just waiting for some hot weather to arrive. I did some fan cooling tests which can be seen here:

  <http://members.rogers.com/michaeljcook/216xt/216xtcooling.jpg>

Subject: 416XT/ ST-7 Desiccant 

From: Michael Hart

>Yesterday I saw the dreaded moisture / ice crystals on the window of my 416.

>I'm wondering what the best recommendation for curing the problem is - how much

>is really required to just refresh the desiccant ? How long does it take Meade

>and how much does it cost for them to do it?

My 416 (not XT) is well over 4 years old and using the same desiccant. I have opened the camera many times. My ST-7 is still on it's second tiny canister of desiccant (much smaller volume than the 416) The first ST-7 canister lasted several months, the second over four years. Both cameras are frequently operated in extreme humidity, well over 2000 hours each. I do not store either camera in any desiccant.

The ST-7 uses two O-ring seals, one in the front and one inside the camera back. The 416 uses one O-ring seal in the front. Both cameras construction (wall thickness, optical window seal, and O-ring seals are capable of holding a partial vacuum or slight pressure indefinitely. If the camera will hold the vacuum/pressure experienced, the desiccant has an indefinite life as well. However, the ST-7 has more leak potential due to more through connections, which I repaired early on, allowing the subsequent 4 year and counting desiccant life.

There are ways of rejuvenating the desiccant in the 416 without removal, which I will not describe here or in private, though removal is the quickest. The 416 does not use a cover glass over the chip (the ST-7 does) which reduces light loss a bit, but risks dust falling directly on the chip. Care must be taken not to smudge/scratch the imaging chip and especially the fine electrically heated shutter actuator wires. A nitrogen purge is good, but not required upon reassemble. Do not use so called "canned air" for a purge because it is not really canned air, but a substance similar to difluoroethane which liquefies under certain conditions related to the cooling of the chip. Dry argon or nitrogen is best.

To cure a premature desiccant depletion problem, find the source of the leaks. If one is in doubt about their skills and/or the camera is under warranty, send it back to Meade.

Subject: Baking the 416XTE Desiccant

From: Geoff Todd <geoffrey.toddbigpond.com> Date: April 2005

My 416XTE is just back in service today after experiencing icing. I pulled it apart and baked the desiccant. It is the third time I have done it -- last time was about 20 months ago. Some additional points from my experience:

1. I get reasonable results from baking 3 hours at 120C. I have tried higher temps but it discolours the desiccant bags (the Meade ones anyway), and I was concerned they might fail inside the camera.

2. It sounds silly but keep track of the various fixings when you take the front cover off and remove the PCB. You will have the 8 allen head countersunk screws (from the cover), two plastic washers and two little nuts (from the PCB) to not lose. There are also two plastic spacers on the studs under the PCB but these can stay put unless you upend the open camera body.

3. Note the orientation of the shutter cabling connector when you unplug it to get the shutter assembly out of the way. The plug does not seem to be polarized but the ribbon cable is colour coded, so keep track of which side is which. You can also remove the O-ring at this time.

4. Be careful lifting the PCB off the Peltier. The chip is bonded to the Peltier (or seems to be) and needs some force to let it loose (or at least mine did the first time). I use a screwdriver under the edge of the slot in the PCB, supported off the camera body with a pencil or similar so as not to damage the rebate for the O-ring. After some gentle persuasion on the side away from the Peltier wires you can feel the PCB let go and then it is not too difficult to get it up.

5. Be careful of the temp sensor wires from the PCB to the camera inner case. They are fragile and could break when the PCB is lifted out of the way to expose the desiccant bags. Of course you could carefully detach the temp sensor to remove the PCB altogether, but then you would have to fix it back somehow with some thermally conductive adhesive. I have not done this.

6. With the PCB hanging off to one side the desiccant bags can removed and put into the oven to bake. Note how they are arranged in the camera body before you take them out. If they don't go back properly they will not let the PCB sit down and the chip will not mate properly with the Peltier. Today I did not have access to the kitchen oven because my daughter was baking my mother a birthday cake, so I used the little sandwich griller in my workshop and it went OK (the T stat is not as good as the big oven, but it was a very nice cake)

7. Make sure that for the three hours or so the bags are cooking, the camera, O-ring and shutter assembly are safe and don't get dusty. I put them in a plastic bag until reassembly time.

8. Before reassembly I give the camera body a vacuum out. I also vacuum both sides of the PCB and around the shutter assembly, and around the O-ring rebate. You don't want to suck the chips off the PCB so use something gentle - I use an old household vacuum cleaner with a neoprene tube about 8mm dia. attached to the nozzle. It gets into the tight areas and gets the dust out without too much force.

9. The replacement procedure is the reverse of the disassembly. I use a little thermally conductive heat sink paste between the chip and the Peltier - just a smear. Check the PCB is not catching on the mounting studs or the inside of the body, and that the chip is seated on the Peltier. There is a little deflection to the PCB when the nuts are tightened - presumably to keep the chip seated. There might be a trick to the O-ring - mine seems too small and wants to cut corners on the inside of the camera. So I stretch it just before it goes back together and then seat it in the rebate and put the cover on before it shrinks back to original size. It is the most tricky part of the whole exercise. Then with the cover on and nipped down but not tightened check right around the gap between the cover and body to make sure the O-ring is in place and has not snuck inside the body or gotten pinched. If OK tighten the screws.

10. It takes a while for the desiccant to take the moisture out of the air inside the camera. Tonight I was in a hurry, put the camera back on the scope, fired it up and started imaging. Tragedy - water on the chip. But it went away after an hour or so with the chip temp set to +0.5C. Then I reduced the temp to -10C for imaging.

11. The data set is very small but there seems to be a correlation between the temps the camera is set to and the longevity of the desiccant - if the camera operates at too low temps it seems to ice up quicker.

If you want email me privately and I can send you photo’s of the trickier parts of the operation. There are also a number of web resources ­ Chris Heapy has some pics on his site.