Trouble with Auto Flats

I’m having a failure rate of about 40% when it comes to taking flats using a manual panel and my ASI1600MM-Pro. The exposure for LRGB flats are respectively as follows:

1.62 sec, 9.5 sec, 2.2 sec, and 8.63 seconds. All get me a desired ~32000 ADU.

As mentioned, about 40% of the exposures end up displaying a pure white screen as viewed real-time in Voyager’s FIT viewer. I have tried adjusting everything available such as USB traffic, ROI, as well as a spread of Max Err % between 5 and 30%.

I’ve been able to take these exposure settings and successfully use them in another program at a USB traffic setting of 80 with zero failures.

I’ve also tried using the USB2 port on my laptop instead of USB3, and ended up with a 100% failure rate, all with white screens. New cables made no difference.

This does not happen during regular subs of any kind. I tend to put a five second gap between exposures, but that isn’t available when doing flats. Might the addition of that feature in Auto Flats be a solution?

Thanks to all for your input.


Have you confirmed that the actual flats look like that in another viewer? I have seen cases where my flat appeared in the viewer as being completely saturated, but looked fine when I looked at them in PI.

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If Voyager say ok to flat and save it the flat is ok. I agree with Bill … i must change setting search for flat, to match stretch. If you look without stretch in raw mode you will see difference. Is on to-do list but im busy now with ASI offset and gain

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I will check that and report back. Thank you, gentlemen.


Interesting results. Using Nebulosity’s file viewer, there was very little difference between a “good” flat and a “white” flat. My target ADU was 32768. The good flat indicated 31792 while the white flat is at 32784. Both are usable as calibration frames according to Nebulosity results.

I don’t understand why one displays this way with Voyager’s FIT viewer, but I’m not going to worry about it.

Leo, you were correct. Raw mode was the preferred setting for auto flats.

Thanks again, gentlemen.


Difference from ADU target can be inside % you choose, if Voyager saved it this mean are ok.

How looking stretch is another question because is only at video… STF stretch are really not linear and work on a border line, flat require different approach from what is used normally from Voyager STF. Better is to use a really linear stretch around mean data. I know how to do that but the problem is to have free time to do it.

We are working on ASI Driver (next daily build), on QHY Driver, on Remote Web Dashboard for Voyager, on Voyager Advanced, on Renting System … so a lot of things running.

All the best

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Leo, this is nothing to be concerned about. It’s a simple matter of clicking on RAW when opening the FIT viewer. All is well after that point, so there’s no reason for you to feel like this is something that’s needed immediately.

Maybe let the viewer “remember” your setting when you shut it down would be easiest to implement. In the mean time, everything works fine.

Thank you for your reply.


Sure , I think to save all but not STF mode …

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