Condensation query

[raymo]

When an astro camera is cooled, how does one avoid condensation on it's
sensor, and probably on the whole camera body? I assume that the sensor is exposed to the ambient temp and humidity through the focuser tube.[ in the case of an open tube scope]. If one were to put an optically neutral window in the focuser tube, wouldn't that fog up?
raymo

[glend]

This is a big subject and the pro camera builders go to great lengths to create dry gas chambers to isolate the sensor from the outside air. Some also use dessicant material to absorb any moisture in the sensor chamber. With DSLRs there is always a small chamber between the sensor and the outside which is covered by a coverglass, most people would think it's the sensor but there is actually a couple of mm gap. Some DSLR modders may put dry gas, like Argon, in that chamber, and/or run a double glazed mod where the LP1 filter is replaced with clear mulitcoated glass to establish an outer chamber. People can also run screw on UV/IR Cut filters on the outer end of the T-adaptor to create another isolation chamber. I fill my modded DSLRs with Argon, and seal them in ziplock bags and this prevents external condensation as well as sealing in the gas. Still I can get external front filter fogging on long nights of imaging when the cooled camera actually starts to cool down the t-thread filter enough to allow it to fog on humid summer nights. The only way to stop that is to dial back the cooling enough for the fogging to reduce and to clean it off - but it can take hours for that 'cold creap' to become an issue. Does that answer your question?

[raymo]

It certainly does, thank you very much, and also puts paid to any idea
I had of cooling my DSLR. SWMBO already hates my hobby enough,
without me spending more time and money on it.
cheers
raymo

[glend]

It actually doesn,'t cost much money, less than than a good EP, but yes it does take time to put together a good working solution. Suggest you readthrough Rowland's thread on DSLR cooling, search the DIY section.

[raymo]

Thanks Glen, I'll do that.
raymo

[glend]

This is the one but start back near the beginning.
http://www.iceinspace.com.au/forum/showthread.php?t=132498

[raymo]

Thanks, I'll do that.
raymo