temperature and noise

[mentos_007]

I notice that when I'm shooting outdoors when it is freezing cold, the digital noise is very rough and visible on my camera (fuji s5000). i heard some voices that low temperatures can cause that digital noise appears in the pictures. but can anybody explain me this from technixal point of view? what's happening then on the sensor? does it need a "special" temperature when it works properly and the noise level is normal? and... can low temperatures harm my sensor? technically speaking?

 

[Polygon]

Materials change their properties according to their temperature. This is especially true for semiconductor materials (they change their electrical properties in a very nonlinear manner regarding temperature) out of which a lot of electronic components inside your digicam (including the sensor) are made. Now there are quite some techniques clever circuit designers invented to mostly compensate for that effects. But a 100% compensation is impossible, so the efforts are made to mostly compensate in a temperature range where the product will be most likely used (usually something around 20°C). If the actual temperature is far away from this optimum you reach areas where those measures aren't able to compensate the effects to a level where you can't realize them anymore (and this will give you some funny effects which might show in image noise, which isn't actually digital because it happened before the signal went though the ADC). This depends on the effort that was put into them and therefore also on the price of the equipment.

How low are the temperatures you are talking about.

About harming your sensor:
As long as the temperatures are within the specifications (they should be in the manual, mostly on the last pages somewhere) of the manufacturer you should be safe of physical damage when using the cam "normally" (what I mean is: Constantly and rapidly heating and cooling the camera in the range of the limits might not be a good idea, but taking it out for a walk in winter shouldn't matter).

 

[mentos_007]

ohh thank you. b y low temperatures I mean something like -10C so not so cold... but the noise level in such temperature, comparing to noise in 20C is wow... huge. and I noticed that when I carry my camera under my jacket, so it is warmer there, and I take it out only to take a photo, the noise is not so rough. but I was interested in technical part. I knew about non-linear manner of semiconductors inside, but I didn't know that this might cause the noise