HEATING temperature controlled cameras

[iapa]

I have been looking at some resources covering cooling cameras wrt noise.

Looking at the noise vs temperature chart for the ASI294MC cooled, at 15C the noise is around <0.2 e/pixel/second.

In my locale an ambient overnight temperature is rarely above 10C overnight in the height of summer, with -10C uncommon during winter.

Should I be considering HEATING the camera to 15C?

Edited March 22, 2021 by iapa

[vlaiv]

Just a small correction - dark current is perhaps <0.2 e/px/s and not noise.

Why would you consider heating the camera?

Important thing is that you have set point cooling camera and you can keep it at steady temperature. This will enable you to do proper calibration with darks.

Say you have 0.2 e/px/s dark current and you are doing 300s exposures. That is 60e of dark current and ~7.75e of associated dark current noise per exposure. That is about x4 that of read noise - so you are approaching limit of exposure length (going longer with single exposure will not bring you further benefit since dark current noise is high enough even if LP noise is not).

Anyway, why not use camera at -15C if you can?  In that case dark current is very low at ~0.0065 e/px/s and for 300s exposure it will total at 1.95e of dark current or ~1.396424e of dark current noise. That is still lower than read noise.

[iapa]

3 minutes ago, vlaiv said:

Just a small correction - dark current is perhaps <0.2 e/px/s and not noise.

Why would you consider heating the camera?

Important thing is that you have set point cooling camera and you can keep it at steady temperature. This will enable you to do proper calibration with darks.

Say you have 0.2 e/px/s dark current and you are doing 300s exposures. That is 60e of dark current and ~7.75e of associated dark current noise per exposure. That is about x4 that of read noise - so you are approaching limit of exposure length (going longer with single exposure will not bring you further benefit since dark current noise is high enough even if LP noise is not).

Anyway, why not use camera at -15C if you can?  In that case dark current is very low at ~0.0065 e/px/s and for 300s exposure it will total at 1.95e of dark current or ~1.396424e of dark current noise. That is still lower than read noise.

Correction agreed.

Why?

Agreed, can set a temperature of my choice.

Why wouldn’t I heat the camera when dark current is so low anyway?

Was just wonder why cool  with the temperature ranges around here.

Previously I have run down to -20C, and was looking for any feedback.

Thanks, as ever, for your comments.

[vlaiv]

10 hours ago, iapa said:

Why wouldn’t I heat the camera when dark current is so low anyway?

Dark current doubles about every 6°C. Higher dark current - higher dark current noise.

When we image, we strive to get the best SNR or signal to noise ratio. This includes minimizing the noise.

Heating up camera will increase noise (however small increase that would be). Why would you want to put an effort towards making your image worse than it can be?

[iapa]

Missed that point duh!.

Brain dead

Thanks