Calibration Frame Temperature Sensitivity

[Farzad_k]

Hi,

I am developing a dark library with a new camera and my hope was to capture (indoors) at -20^dC. However, the capture started that way and then migrated gradually to -18 degrees. Is this going to be a problem?

The camera is a QSI 6120.

Thanks

Farzad

[Niall Saunders]

Hi Farzad,
What about integrating 5 (or so) Draks from the start of the run, and a similar number from the end of the run. Divide the averaged integration from the start by that from the end and then look at the reultant image.

What does it look like? If the two subsets were statistically equivalent, then the result of the division process should give you an image with an averaged ADU of 1.000 - what sort of result do you get?

[Farzad_k]

Niall,

Thanks for the input. I only can understand some of what you are saying: do integration of X subs at the lowest temperature and X at highest, and compare the "average" of the lowest to the "average" of the highest. If the two averages are "statistically equivalent"...

I don't know how to figure that out yet, and I don't know what a division process has to do with anything.

Basically what I wanted to know is if there should be a concern if there is a variation of a couple of degrees in between the subs in general, and between the future light data and the master dark frame.

I will think about your suggestions though.

Farzad

[chris.bailey]

Have you tried running statistics on a few frames at -20C and ones at -18C to see what the differences are? The 6120 has a delta of 45C so assuming your house is at 20C plus I can see why the CCD is struggling to maintain -20C. On a couple of my CCD's the dark statistics are different if the peltier is running full whack than when it is running at say 70% so in my view it is best to take calibration frames at similar ambient temperatures to the lights.

[Farzad_k]

I had not compared statistics, and would not know what to look for except that I could probably make a judgement based on variations and how excessive they may or may not be. Thanks for the idea.

Yes, I have dealt with the ambient temperature and have been able to produce the subs that are consistent.

Thanks for the reply and input.


Farzad