From: Milton Aupperle <milton@outcastsoft.com>

Date: February 8, 2006 3:29:08 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Luna_20060206_MJA.jpg


Hi Alan;


On 8-Feb-06, at 2:59 PM, Alan Friedman wrote:

Hi Milton -


Could you say more about the noise reduction achieved with the cooling unit? I have always thought of temp related noise to be an issue with CCD chips used at relatively long exposures rather than the short exposures used for planetary imaging. 


I have not had any time to even try to quantify the noise issue - but there is a difference with the Flea cameras for sure. I suspect this applies to all cameras too.


The basic premise is the faster you run electronics ,the more heat it generates and the hotter electronics run, the noisier they get. And most of the noise I'm talking about is pixel random variance noise. In an ideal system with no noise, the difference between two images taken with the same cameras should be zero but it isn't.


BTW, when I used my DMK camera at 30 second exposures on the ring nebula this past summer I was surprised to see very little evidence of noise in the raw frames. 


The Flea is a very compact piece of electronics - so it's all packed in their very tightly into a space slightly less than a 2.5cm / 1" cube.  When running at 60 fps the outside of the camera warms up by about 13°C / 23°F above ambient temperature. Even with short 10 second exposures, cooling by 20°C makes a considerable difference in noise levels visually.


It really depends on the camera layout, gain levels and size too You could fit around six  "Flea" cameras into the same space that a single DMK cameras occupies.


HTH..



thanks -

Alan


On Feb 8, 2006, at 4:36 PM, Milton Aupperle wrote:


 I did however get to run the Flea camera with my external peltier

 cooler unit, which dropped the camera from the ambient temp of about

 -5°C to  -25°C. A layer of ice was coating the outside of the camera

 by the time I stopped imaging. This reduced image noise a fair bit -

 but I have no quantifiable numbers on how much.


 TTYL..


 Milton Aupperle


Milton J. Aupperle

President

ASC - Aupperle Services and Contracting

Mac Software (Drivers, Components and Application) Specialist

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