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Cooling for Watec 902H2 Ultimate?

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#1 Michael Morris

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Posted 21 August 2013 - 11:20 AM

Having just taken delivery of a nice new Watec 902H2 Ultimate for meteor observing. I've noticed that a limiting factor on how high I can usefully set the gain to is at what level camera noise triggers the motion detection algorithmn on the capture software (HandyAvi). Has anyone experimented with cooling a 902 camera to see if it reduces this noise and hence increases the effective sensitivity?

#2 mattflastro

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Posted 22 August 2013 - 10:19 AM

Having just taken delivery of a nice new Watec 902H2 Ultimate for meteor observing. I've noticed that a limiting factor on how high I can usefully set the gain to is at what level camera noise triggers the motion detection algorithmn on the capture software (HandyAvi). Has anyone experimented with cooling a 902 camera to see if it reduces this noise and hence increases the effective sensitivity?

Your camera has a huge amount of gain of up to 60dB (both AGC and manual gain modes).
At the same time it has a signal to noise of 50dB min.
Experimenting with this particular camera is not necessary in order to determine if it's worth cooling.
The answer is a clear yes, and here's why:
- at a gain of 60dB applied to a video with a signal to noise ratio of 50dB, you will get the video signal about 10dB UNDER the noise level.
- in order to restore the video and be able to see the video not the noise, you need to improve signal to noise by at least 20dB.
This way you'd be left with a modest signal to noise of 10dB , noisy but viewable .
In order to achieve 20dB of noise reduction you need to reduce the CCD temperature. For each 6 degrees of temperature drop the noise halves or drops 6dB.
Since you need 20dB of noise reduction, you need 20 deg of temperature drop.
This can be acomplished with a single stage Peltier but some precautions are needed in order to avoid dew and electric noise from the TEC circuitry from getting into the analog video and CCD read circuits.

#3 Michael Morris

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Posted 22 August 2013 - 04:31 PM

Thanks.
Being completely cackhanded there is no way I'm opening up my expensive new camera. I'm planning to add a heat sink and fan to the outside...

#4 mattflastro

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Posted 22 August 2013 - 04:38 PM

Thanks.
Being completely cackhanded there is no way I'm opening up my expensive new camera. I'm planning to add a heat sink and to the outside...

Before doing any work , there are simple ways to figure out if it's worth doing it like that.
For example let the camera run for some time and use an IR or laser thermometer to check its temperature on the outside, in the front area around the mount , both before powering up and after letting it run and heat to build up.
If you see a significant temperature increase, then you most likely could improve it by cooling just the outside.
Also, you can cool the outside just for testing with some dry ice in a small amount , or any other such means. Whatever you do, just don't get the camera wet. You will be able to see if cooling the case reduces the noise enough.

#5 Michael Morris

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Posted 28 August 2013 - 07:24 PM

I've just bought a mega cheap peltier cooler, fan and heat sink to experiment with (just over £5 the lot, including postage). I'm not expecting low noise cooling performance, but I just want to experiment for now. I'll let you know how I get on with it.

#6 Puck Ja

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Posted 28 August 2013 - 08:02 PM

I will be interested in your result. You can just shoot a dark frame (even in house) with and without cooling. It should be very quick to find out the difference.

Just a thought. I plan to do that to my Lodestar_C. :)

#7 Michael Morris

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Posted 29 August 2013 - 04:25 PM

[quote name="mattflastro"][quote]Thanks.
Before doing any work , there are simple ways to figure out if it's worth doing it like that.
For example let the camera run for some time and use an IR or laser thermometer to check its temperature on the outside, in the front area around the mount , both before powering up and after letting it run and heat to build up.
If you see a significant temperature increase, then you most likely could improve it by cooling just the outside.
Also, you can cool the outside just for testing with some dry ice in a small amount , or any other such means. Whatever you do, just don't get the camera wet. You will be able to see if cooling the case reduces the noise enough. [/quote]

Just tested it and the difference between off and on (for 20 minutes) is 4 deg C. Outside temperature was 20 deg C.

#8 mattflastro

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Posted 29 August 2013 - 04:54 PM

[quote name="Michael Morris"][quote][quote]Thanks.
Before doing any work , there are simple ways to figure out if it's worth doing it like that.
For example let the camera run for some time and use an IR or laser thermometer to check its temperature on the outside, in the front area around the mount , both before powering up and after letting it run and heat to build up.
If you see a significant temperature increase, then you most likely could improve it by cooling just the outside.
Also, you can cool the outside just for testing with some dry ice in a small amount , or any other such means. Whatever you do, just don't get the camera wet. You will be able to see if cooling the case reduces the noise enough. [/quote]

Just tested it and the difference between off and on (for 20 minutes) is 4 deg C. Outside temperature was 20 deg C. [/quote]
Having only 4 deg C temp increase on the outside means the CCD is very well insulated from the enclosure. You would need to apply some really heavy duty cooling to the encolsure to have some effect on the CCD .
Try the ice cubes test , cool the camera enclosure . A very simple test is to leave it in the freezer for some time .
Before you take it out, have everything in place to just plug it in and power up , including monitor on.
When you power up you'll be able to see for the first few seconds the noise level with a cool sensor. After 5-10 seconds the CCD die starts to warm up already due to its internal heat dissipation , even if the camera is still cold to the touch.

#9 Puck Ja

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Posted 30 August 2013 - 12:00 PM

I did the test on my Lodestar_C and I can see huge difference at current weather (outside ~90F vs out of freezer 1 min ~40F).

I am really afraid the condensation will short the internal circuit since none of these CCD are sealed. So I only take one 60-sec shot for comparison and then stop.

@Matt: I really like to cool my Lodestar in a more safe way (sealed). Do you or any one you know may provide such service to mod the CCD for cooling?

Thanks!

#10 mattflastro

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Posted 30 August 2013 - 02:30 PM

I did the test on my Lodestar_C and I can see huge difference at current weather (outside ~90F vs out of freezer 1 min ~40F).

I am really afraid the condensation will short the internal circuit since none of these CCD are sealed. So I only take one 60-sec shot for comparison and then stop.

@Matt: I really like to cool my Lodestar in a more safe way (sealed). Do you or any one you know may provide such service to mod the CCD for cooling?

Thanks!

Yes, you're correct. This is just a test to evaluate if it's worth cooling it or not.
For a permanent solution, it needs to fulfill several requirements.






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