With unregulated cameras, do you do warm-up exposures to get a better result?

[ELS]

It seems like it would be a good idea to warm up the sensor before taking the exposure(s), so the noise pattern is more stable and your calibration frames are more accurate.
Does anyone do this? does it help? and how long should the exposures be to warm up the sensor enough to be close enough to the final temperature for a good result?

[Elp]

Heat is generally detrimental for imaging, you want to reduce it more than anything. Turning off the LCD display or if it articulates, moving it away from the body helps.

[Elp]

If you've ever experienced an astro camera you'll see the stark difference temperature makes whilst it's cooling down.

[Elp]

With a body, I tend to take calibration frames once the temperature has kind of stabilised based on ambient, you may find it never does really due to ambient changes, I usually take them at the end of a run.

With a DSLR body, you get much better noise reduction by imaging for hours on a target. A banding reduction operation is sometimes needed, it's a one button click in Siril.

Pretty much all AP images of DSOs have had post process software noise reduction applied though few like to admit it, I learned this early on as even my cooled astro cameras produce noise, but it's much finer and less pronounced compared to a camera body.

Edited August 4 by Elp

[ELS]

That wasn't my question.
I meant that since the sensor is gonna heat up anyway, wouldn't it help to warm it up before to the final temp so the calibration frames are accurate across all the frames instead of just the latter ones?

[vlaiv]

6 minutes ago, ELS said:

That wasn't my question.
I meant that since the sensor is gonna heat up anyway, wouldn't it help to warm it up before to the final temp so the calibration frames are accurate across all the frames instead of just the latter ones?

I don't know exactly and I guess it will vary between sensors and ambient temperature and how good cooling is implemented (although it's not active cooling - cameras still have passive heat sink type of cooling on sensors).

It also depends on exposure length. I think that most sensors under "normal" conditions (not too warm nor too cold) hit equilibrium temperature after one or two exposures.

If you are using astronomy cameras - you will have that information saved in fits header - then you can use various software to examine this information from file to file and see how long it takes for it to stabilize under given conditions. Some imaging software has real time readout of temperature sensor of the camera - so you can just watch that. Keep in mind that having timeout between exposures makes temperature go down for a bit before next exposure as it starts cooling as soon as it finishes the exposure and this can impact results.

[vlaiv]

I just realized that I did not answer the question and answer would be - no. You don't need to do warmup subs. If you wish - you can always discard first few subs that have significantly different temperature by examining camera temp recorded with sub.

If you have well behaved camera - you could try to do dark scaling to calibrate with darks. This ensures that you still end up with good calibration even if there is difference of few degrees between darks and lights.

Mind you - you will have temperature drift of few degrees even when your camera is up to "working temperature" as conditions change over the course of the evening and ambient temp can change for few degrees easily - and so will equilibrium sensor temperature with it.