An important note on astronomical CCD camera purchases

[rcj]

Hi all,

Thought I would write an important note here for anyone who decides to buy an astronomical CCD camera and is using it in Singapore and Malaysia (tropics). Please! Before you embark on a few thousand dollars worth of your precious money into one of these jewels, please make sure that the CCD chamber is reputed to be extremely vapour free, or tight such that when the cooled camera goes down to low temperatures or even sub zero, condensation build-up or frosting will not occur. If it does, good luck to you, unless you know that there are dessicant based devices (or alternative methods) that can assist in combating this issue, the camera is next to useless. This I am putting forth as an important warning to potential buyers is because I myself was a victim and experienced weeks of frustration with the SBIG ST series. There is nothing bad about the series, just that somehow even with reassurance from the company, the camera just cannot take the high humidity here and will frost up at zero degrees temperature even with the dessicant plug in place to apparently keep the frost at bay. It did not. Luckily, with the kind advise of Particle Wave Technologies' Sharin, there was a compatible ST dessicant plug system that they made that was even 'stronger' than the offering from SBIG, and it managed to solve this issue. However, I found that whenever I go for trips, and the camera is experiencing a range of temperature differences, at the end of the trip, when back in Singapore, the frosting will come back again, but since I have a few dessicant plugs, I would just insert in replacement, and the new one will dry out the CCD chamber and eradicate frosting. When not in used, the camera is placed in the dehumidifier at all times.

It seems that the ATIK cameras have this issue as well, and similar cooled cameras of other makes. I have made a few exchanges based on the above phenomenon from other local CCD imagers, and they have the same issue. So far, the starlight express cameras are doing well in this regard, but then again, one can never be sure until you doubly confirm this with the manufacturer and perhaps even ensure if full refund and returnable policy could be accepted if the worst case happens and you cannot find a solution to the above issue.

So before you embark on the purchase, and with everything else in place for your dream setup, please do not cry if suddenly this happens and your imaging session is ruined indefinitely! I did! but is solved now, and I hope it goes well for you too!

[rcj]

incidentally....perhaps it would be a good idea for those with ccd cameras to discuss their experiences (if any, hope not!) with this frost/condensation issue and how you overcome it.

[JY]

Hi,

- I had a ST8 for years and it frosted below 0C. Not much of a problem, I imaged at 0C (this is still 25 degrees cooler than the air temperature in Singapore) and all was fine using Dark Frames.

- I now have had a new ST8XME for 6 months. No problem. I have tested it at -15C (with water cooler), no problem. I usually image at -5C without the water cooler - no frosting.

JY

[rcj]

Hi JY,

I think I remembered you saying that it was not an issue for you last time. Think the ST8 is magical! However, I think others like YKChia and Matthew had a similar issues with their cameras...

[vhuang168]

FLI cameras are purged with nitrogen, iirc. So should be better.

Vincent

[kochu]

If I had one such a costly piece and found myself in such a &%#^ , I would have tried to create an anhydrous atmosphere inside the telescope, even if it amounted to do some invasive surgery on the scope.
After all the bulk air which seeps to the sensor , probably must be from inside the scope.

May sound crazy engineering , but still some food for thought.

Kochu/21-9-07
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[rcj]

then a newtonian might not be feasible... or any open tube...

[JY]

The CCD chamber in a SBIG camera is sealed.
Unless you remove the desicant plug, no air/humidity goes inside the chamber onto the CCD.

[kochu]

Yes Open tube is a problem , unless you are willing to pipe your laptop exhaust (FOC) into your Newt tubes . For closed scopes Turrets can be used to insert dessicant plugs.

Kochu/21-9-07
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[rcj]

the thing is it still remains questionable how effective sealed it is. Perhaps it can only be usable in mid humidity levels. In areas where the humidity is extremely high, somehow the seal is not as effective. How well the manufacturer knows or designed the seal to be is then in question. Apparently the stock SBIG plug is not as effective as the one supplied by PWT, well at least for my camera.