Batch Preprocessing - Script - error message

[Juan Conejero]

Try what happens if you deactivate "Optimize Dark Frames"...

Thanks for that hint . It worked: doughnut gone!

Note that the fact that dark frame optimization invalidates your flat frames reveals a problem with your calibration procedure. Disabling dark frame optimization should not be seen as a solution, but as a symptom.

Are you using bias frames? Biases are *necessary* for correct calibration, and mandatory for dark frame optimization.

[georg.viehoever]

...Note that the fact that dark frame optimization invalidates your flat frames reveals a problem with your calibration procedure. Disabling dark frame optimization should not be seen as a solution, but as a symptom.....

Hi Juan,

Tests I did suggest that the theory that (dark-bias) is linear with exposure time is not entirely true for CanonEOS cameras, especially for exposures<120 seconds (I think we also had a thread on this in the forum, I just cannot find it right now). This may be the reason why DarkOptimization sometimes fails for these cameras, in particular when using darks with exposure different from those of lights. Indicators of this problem are "unusual" scaling factors displayed in the console window. Switching off DarkOptimization simply produces better results in these cases.

The fact that the 1.26 version did not correctly group dark exposures may also have contributed to the problem.

Georg

[Juan Conejero]

Tests I did suggest that the theory that (dark-bias) is linear with exposure time is not entirely true for CanonEOS cameras, especially for exposures<120 seconds

I know and agree with that. However, if a reasonably correct data set is used:

- A large number of bias frames (mandatory).

- Dark frames appropriate for each group of flats and lights, that is, with similar exposure times and temperatures.

then our dark frame optimization routine always produces better results in SNR terms. I have working DSLR data sets (those that we use for tests) that demonstrate this with dark scaling factors in the 0.85 - 0.95 range.

My comment was just to stress the need of biases and the fact that analysis tools (such as dark frame optimization factors) should always be taken into account for improvement.

The fact that the 1.26 version did not correctly group dark exposures may also have contributed to the problem.

Darks were correctly grouped. The problem was with flat and light frames, and it was only a cosmetic GUI problem (incorrect visual grouping of tree box items); the script selects frames correctly as a function of binning, filter and exposure time, as appropriate.