Cooling Temperature

-10 degC. -20 degC is at risk of frosting the sensor in my usual weather.

-20degC would be better, -10 degC just makes the grade. Noisy sensor.

I will go as low as my ZWO camera will allow as long as it doesn't exceed 80% power at the start of the session. As the temperature drops during the night, so does the power consumption.

Just watch the sensor reading, it only takes about 3 mins to hit the target temp.

-20C is my norm on cold nights, but I usually raise to -15C, -10C or -5C during the warmer summer nights.

Eddie

With my FLI 16803 Proline I can manage -30Celsius all year round. Probably excessive but it works.

Here is Robin Glover's timeless talk on Gain, sub exposure lengths and temperature:

https://www.youtube.com/watch?v=3RH93UvP358

Both dark current noise (which depends on sensor temperature) and sky background noise increase with total exposure time. The goal behind setting a certain sensor temperature is to make the dark current noise small with respect to sky background noise - in other words, make sure that sky background noise, which you cannot control, is the dominant noise term  compared to other noise sources such as dark current noise and read noise. 

If you are imaging from a relatively dark site, or doing narrow band, you will certainly benefit from going as cool as you can consistently go. From a relatively light polluted site, there is little or no benefit to deep cooling.

Hi,

There is an ongoing thread with similar question for a ZWO 533, where I replied the following:

"
I usually have a 5 min ramp to cool and to warm the camera. But let me challenge you in one thing: maybe you don't need to cool to negative temperatures, as thermal noise of that camera is quite low. As far as I can see in the website, the thermal noise is as follows:

T (ºC)     DarkCurrent (e/s)    ThermalNoise (e (300sec))
0                    0.00195                               0.765
-10                0.00050                                0.387
-15                0.00025                                0.274

In the last column, you have the thermal noise of a 300 sec exposure.

Depending on the sky you shoot, your shot noise for the same 300 sec exposures (considering a color camera and an F5 telescope) should be:

Bortle                 SkyBack (e/s)                 SkyBack (e (300sec))                 ShotNoise (e )
2                                0.30                                              90                                    9.49
4                                0.57                                             171                                 13.08
6                                3.97                                           1191                                 34.51
8                                8.30                                           2490                                 49.90

Since you add noises using the quadrature rule, and considering the worst case (0ºC), the combined noise is as follows:

Bortle                 ShotNoise (e )               Total Noise (e )
2                                    9.49                             9.52
4                                  13.08                           13.10
6                                  34.51                           34.52
8                                  49.90                           49.90

So, you should be fine shooting at 0º or even a bit higher as it barely contributes to the noise and has several advantages such as less stress on the sensor and lower power consumption.

Just a thought... 

Note: I have assumed an OSC camera with clear filter. Final conclusion may vary according to filters used or mono/OSC.
"

In short, you should compare with the shot noise you'll have at your shooting site but unless you are doing narrowband, it is likely you don't need to cool that much.

André

D. Jung:
Don't forget the camera only has a 14bit ADC. With a 20ke full well, your resolution is 1.4e.

*
The ASI533MC has a FWC+ of around 50ke-.

As I wrote?

Below is a comparison between two master dark frames for the 533 colour sensor, each of 180s,  showing the central portion at 1:1 scale. Left is @ -20 degC, right is @ -10 degC:



It is obvious why -20 degC is better than -10 degC.

I live in the deep southern USA. Very hot and humid summer (most of the year), with cool winters. I run my 533 at 0C in the summer and -10 in the winter.
I really don't like to stress the TEC and I have not found any end result reason to do so. I see little to no difference in the final result running either temperature.

Jim