cooling options

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elken2004
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Joined: Tue Feb 14, 2017 7:34 pm

cooling options

Post by elken2004 »

Hi Robin,
I think an option of staging cooling would be useful
IE

Say set a point of -10 degrees, and in options have it do it in stages by settings, as in first it will goto +5 first sit for a designated period of time then move to say 0 degrees, then after say five minutes drop to -5 then sit for say five more mins then move to -10 etc

The intervals can be user set, according to camera characteristics and also ambient temp, I f ambient is high like 25 C use greater time intervals as I have found this makes a difference.

My tests have been based on the ZWO asi1071mc cooled. It would pretty much across the board for any of the desiccant type imagers.
cheers
Clive
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admin
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Re: cooling options

Post by admin »

Hi Clive,

I may be being dim here, but what's the benefit in this case to staged cooling? You mention dessicant so I guess it has to be something to do with humidity, but I'm not seeing it I'm afraid.

cheers,

Robin
elken2004
Posts: 29
Joined: Tue Feb 14, 2017 7:34 pm

Re: cooling options

Post by elken2004 »

Hi Robin,

Sorry to confuse,
I was suggesting it, based on thermal shock theory, of when it is at a high ambient temp of say 20 C, and suddenly it is cooled rapidly down to -15 and if there is any moisture, the sensor glass fogs even if it sublimes away you can end up with particles left on surface where frost forms.
I have serviced CCD's a few times and if frosting has occurred, there is often a residue as a result.
Also sensor life will be extended, if a practice of staging is applied.

Just as an additional note, yesterday I opened the 1071 and removed all tabs, 3 x inside around the sensor and the 2 in the aux plug.
I baked them for 1 hour, and using proper optical cleaning practices cleaned the sensor glass.
If you breathe on it you can see the effect of where previous frost had formed, after cleaning it was clear of all of those 'patterns'
I then reassembled the unit. and 2 hours later staged a cooling down to -20 and did not even have the slightest trace of fogging or frosting.
I did this over 15 mins.
Considering how much money these cameras cost treating them the best way ensures longevity.

cheers
Clive.
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Re: cooling options

Post by admin »

Ah, Ok.

I would have expected some warning from the manufacturers if thermal shock from a physical point of view were expected to be a significant problem, but I can see that there is an issue with humidity control during the cooling process. I'm pretty much only fixing bugs now for 2.10, but will keep this in mind for a later version.

cheers,

Robin
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