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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Dark Flats

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Replied by ALESSANDRO PENSATO on topic Dark Flats

Any news?
3 years 8 months ago #56440

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Replied by ALESSANDRO PENSATO on topic Dark Flats

Any news?
The following user(s) said Thank You: Scott Denning
3 years 7 months ago #58788

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Replied by Roland Roberts on topic Dark Flats

I'll second this. I've gotten used to having dark flats as an option in other DSLR control programs and, from what I can tell, the recommendation is to use flat darks/dark flats for calibrating your flats for any CMOS based sensor rather than bias frames and scaling which would include my ZWO/ASI cameras.

For all practical purposes, I'm really just looking for a label on the files; near as I can tell, there is no standardized FITS imagetyp keyword for this, so it's really a convenience for me to organize my files correctly.
3 years 5 months ago #61760

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Replied by Wouter van Reeven on topic Dark Flats

In that case I repeat my comment at the top of this thread: simply create darks with the same exposure time as your flats and then rename the folder from Dark to DarkFlat and rename the files in that directory in a similar way. I agree that it would be much more convenient to have the possibility to select a DarkFlat option in Ekos but until then this is a perfectly viable option. It is possible to write a bash script to do the renaming automagically if you want though it may be tricky if you have both Darks and DarkFlats in the same directory.
The following user(s) said Thank You: Richard Beck
3 years 5 months ago #61764

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Replied by Peter Sütterlin on topic Dark Flats

Well, Flat Darks are not different from other Darks, is it? But if you only want to easily see which type they are, just add the exposure time or a timestamp to the filename for those type of darks?
3 years 5 months ago #61994

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Replied by Giles on topic Dark Flats

As an ASI camera user, who seems to be getting poor results using Flats at all I would like to suggest a couple of changes:

1. Flats - An option to set the number of significant digits for the exposure time, for instance, I don't want an auto-calculated exposure time of 0.534323 seconds, just make it 0.5 seconds, or 0.53 seconds.
2. Dark Flats, would be nice to have a check box in Flats to say also create Dark Flats, then when all the flats (after going through all the filters) in the sequence are done, bring the pop-up to cover the scope, allow user to select OK, and rerun the Flats sequence again (but without autocalculating the ADUs for each filter and just using the exposure time used for the flats.).

For (2) - it would be good if I only have to remove the flat light source and cover the scope once in the whole process (8 filters in the wheel).

The above would help me enormously in testing with different ADUs.

I seem to get best results with just Darks and Bias, despite having a ZWO camera (although it is a Pro, so has the 256MB buffer).
3 years 5 months ago #62042

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Replied by Alex Varakin on topic Dark Flats

I take flat darks in Ekos as just regular darks and feed them into Weighted batch processing script and it figures out that these darks apply to flats because they have same exposure. Never felt a need for special feature in Ekos
3 years 4 months ago #62333

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Replied by Giles on topic Dark Flats


If you use the auto-ADU feature for your eight filters in your filter wheel, then all your flats have different exposure times, like 0.54723 seconds or similar. It is a real pain to construct another 8 jobs with each filter having the exact same exposure time, you have to note down 8 x exposure times, each with around 5 significant digits.

And, yes, I could do 0.55 seconds and reduce the number of significant digits, but my processing software complains that the exposures for dark flats are different from light flats.

I can see this is not so much an issue for one-shot-colour users, but for those composing LRGBHaOiiiSii images, it is a bit of a pain.
Last edit: 3 years 4 months ago by Giles.
3 years 4 months ago #62340

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Replied by Nick Birkett on topic Dark Flats

Yes I agree. My 10c worth:
What I do is take Flats using the auto-exposure option in "Calibration Options". After the flats are complete I double click on each of the
flat jobs and edit them by changing Flat to Dark then click the tick button. I then have a set of Dark jobs that have an identical exposure to the Flat jobs (and don't forget to switch off the flat light and cover the scope - yes !!).
But it would be a nice feature if I could just click an option eg copy flat jobs to darkflat jobs . This might also save me having to rename all the resulting Dark frames as DarkFlat which I do just to keep things tidy. Not a critical option but a nice one to have I'd say.
2 years 2 months ago #79226

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Replied by Jasem Mutlaq on topic Dark Flats

What would be an intuitive option? Add Flat job, then create a dark flat immediately afterwards?

i.e. if we have LRGB flats, do we make it L flat, L dark flat, R flat, R dark flat.. or LRGB flats, then LRGB dark flats? any advantages or disadvantages?
2 years 2 months ago #79227

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Replied by Giles on topic Dark Flats

That would require a lot of covering and uncovering the telescope if done manually.
I would prefer doing all filters for flats, then converting the sequence to dark flats.

Then I just have to arrange light source once, and scope cover once.
The following user(s) said Thank You: Jasem Mutlaq
2 years 2 months ago #79228

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Replied by Nick Birkett on topic Dark Flats

If the Flat->Dark option was after the last flat job it could convert all flats to darks and then you would only have to turn off flat light and cover scope once (like doing it manually). eg option : (Copy all flat jobs to darkflat jobs). I guess the problem would be that the exopures of the flats are only known once the flats jobs are instigated (using the auto exposure option).
2 years 2 months ago #79230

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