Batch PreProcessing

[Jules]

Hi

When running this script I keep seeing an error in the process console , 'no correlation between master dark and target frames (channel 0)' with the resultant none calibration of some my images.

The dark image length is exactly the same as the light image length. I have even shot a new series of darks and I still see the same problem?

PI 1.8 RC5
OSX 10.8.2

[Geoff]

Hi Jules
Do a search on "no correlation between master dark and target frames".  You'll get lots of hits.
Geoff

[Jules]

Hi Geoff

Thanks for that.

Regards

Julian

[Jules]

Hi Geoff

Yes there is a lot of hits with respect to that particular message. If I understand correctly then there is not a lot you can do about it.

I even created a dark frames with Maxim and run the calibration routine with exactly the same results?

Regards

Julian

[f11]

Hi Jules,

On my machine, at least, that message comes up as a "Warning", and just tells you that PI determined that applying the dark frame to the light frame made the resulting frame noisier, so the dark wasn't applied and the light frame was left as is.  Since its a warning, I don't worry about it - much.  I DO notice that if you have a LOT of light frames that generate this Warning during dark application, the resultant stack of lights after integration seem more coarse in appearance.

I did find that these warnings more frequently show up when the duration of the dark frame is REALLY different from the light, ie. a 600s dark applied to a 3s light (a bunch of 3s images of C2011/L4 in near twilight recently).  I did some 180s darks just to test my thinking, and when applied to the 3s light frames the Warning didn't show up and the darks were applied.  The resulting stack of integrated light frames looked better for having the darks applied... but that may be just my imagination.

Don't know if that helps or not.
Rod

[Jules]

Hi Rod

I have had to look at my system to see what has changed and find the cause of my problem.

I read an article on the QSI website saying that when I was binning 2x2 I should be using low gain. I tried this and start having problems with application of darks against  (low gain) lights.

I found that none of my high gain darks would work on my low gain lights. I have now switched back to high gain for 2x2 lights and every thing seems OK now.

I could not see any visible difference with high / low gain on my images?

Regards

Julian