Does this flat look right?

[carl20171]

I see most posted flats look all white with a little black around the edges. Mine are coming out black on the edges and white in the middle. They seem to work though? I am using an Atik 490 mono CCD and on Maxum the saturation is 23000. Does anyone else have flats like this?                                            

[carl20171]

I know this one looks burnt out in the middle because I saved it as a low res jpg for the upload. The white part looks much better as a FITS file. Its more the color layout I am questioning.

[ollypenrice]

That looks like a good flat which has been given an excessive stretch before being black clipped. I suspect that some processing is being performed, perhaps unintentionally. It is quite possible that the linear version of this would look like a normal flat. Essentially a classic flat has darker corners and a brighter middle, as here.

Olly

[carl20171]

Thank you.  This is how each individual photo looks on the computer screen also before saving. I tried to look at it  in linear and log and gamma with max pixel or screen stretch and it always looks pretty much the same. I guess the thing is even though it looks unconventional that it is ok to use. It does seem to make the lights slightly better not worse. 

Thanks for all the help Olly    I wish I knew you were there 2 years ago when I was in Cannes for the film festival. 

[carl20171]

I made some progress. If I go to screen stretch and make the range from 23000 to 27000 it looks like most other flats. I guess the question is should I do a permanent stretch to the files to make a master where they look more like conventional flats or just use them as is? 

[ollypenrice]

Thank you.  This is how each individual photo looks on the computer screen also before saving. I tried to look at it  in linear and log and gamma with max pixel or screen stretch and it always looks pretty much the same. I guess the thing is even though it looks unconventional that it is ok to use. It does seem to make the lights slightly better not worse. 

Thanks for all the help Olly    I wish I knew you were there 2 years ago when I was in Cannes for the film festival. 

I wish I'd been at the film festival!!

lly