Thermal Noise on CMOS

[Dave Gray]

Hey Guys,

Hopefully someone tech from Red can answer this but anyone with the knowledge please jump in. Just doing a little section on digital noise in my thesis and have a question.

As CMOS noise if primarily effected by thermal noise and flicker noise. I was wondering if there is a increase in noise from the sensor when you leave the camera running for hours or say are shooting in the desert (even at a level you can't really detect in the image)?

Cheers
Dave G

 

[Dave Gray]

No one? :crying:

 

[Daniel Browning]

As CMOS noise is primarily effected by thermal noise and flicker noise

Thermal noise goes with temperature and time for CCD as well as CMOS. In all the camera measurements I've seen (even those with 2.5 e-/pixel read noise), it's never a problem for shutter speeds faster than 1/10 at room temperature. RED ONE runs significantly hotter than room temperature, though.

I was wondering if there is a increase in noise from the sensor when you leave the camera running for hours?

I haven't done or seen any thermal noise measurements; however, if the thermal noise was powerful enough to rise significantly higher than the read noise (flicker noise) in normal circumstances (running for hours), it would have been discussed by now. However, if thermal noise only raised the noise floor slightly higher than typical read noise, it would likely not be discussed because most people set the black point well above the noise floor anyway. Jared has stated long ago that he had a RED ONE running continuously for at least several weeks, and there was no problem (though he didn't specifically state that noise level stayed the same).

...or say are shooting in the desert?

I don't know if there have been any reports of increased thermal noise in hot circumstances, but I have seen plenty of noise discussions with regard to slow shutter speeds, such as 1 second interval recording.

 

[Dave Gray]

Cheers Daniel :thumbsup:

 

[Charles Angus]

You can see thermal noise issues on DSLRs with very long exposures, hot circuitry in the camera can heat the sensor and make nasty bright patches in the image.

You might find some info through astrophotography avenues, they might have to deal with these issues.