Flat over correction using APT

[simmo39]

Hi all. I seem to be having problems with over correction from my flats. ( Light corners ) I can remove most of it during processing but would like to make my life a bit easier. In APT I can't remember whether I need increase the ADU or decrease it. I'm using at the moment my SW 72ed and was wondering if anybody else is using APT with a ASI 1600 mm and what ADU you are using.

Thanks in advance. 

Btw merry Christmas.

[knobby]

I haven't used flats as yet ( I let gradient Xterminator  do it's stuff) I know I should but just haven't yet.

I found this thread useful however 

 

[simmo39]

1 hour ago, knobby said:

I haven't used flats as yet ( I let gradient Xterminator  do it's stuff) I know I should but just haven't yet.

I found this thread useful however 

 

Hi and thanks for the link. I have been through it and I'm still at a loss at witch way to go with ADU settings. At the moment I have it set at 18500 and this worked fine with my SW 130 PDS but not with my 72 ed. If in getting light patches in the corners I'm guessing I'm over compasating and need to lower the ADU. I think just trying to confirm. My brain hurts! Lol

[ollypenrice]

Are you calibrating your flats with flat darks? (With CCD you can just use a master bias for this but wth CMOS you must make darks at the same settings as your flats.) Uncalibrated flats may well over-correct. However, I've had this problem arise out of nowhere and evade explanation so there is no guarantee that flat darks will work.

Olly

[simmo39]

1 hour ago, ollypenrice said:

Are you calibrating your flats with flat darks? (With CCD you can just use a master bias for this but wth CMOS you must make darks at the same settings as your flats.) Uncalibrated flats may well over-correct. However, I've had this problem arise out of nowhere and evade explanation so there is no guarantee that flat darks will work.

Olly

Hi Olly, yes using flat darks. It seems so strange as the images I did last night seem worse than usual although I have had the problem since switching scopes.

 

[newbie alert]

Ive had problems in the past of over correcting by having the adu too high..if you have dust bunnys then they will show after applying( light circles) but a adu of 18500 would seem too low for me..I aim for 22000... so the dust bunnys would be undercorrecting( dark circles) 

I've not tried flats in APT yet..

[simmo39]

12 hours ago, newbie alert said:

Ive had problems in the past of over correcting by having the adu too high..if you have dust bunnys then they will show after applying( light circles) but a adu of 18500 would seem too low for me..I aim for 22000... so the dust bunnys would be undercorrecting( dark circles) 

I've not tried flats in APT yet..

Thanks for the reply, Next chance I get I will try that as a base setting.

[simmo39]

For those having the same problem I set my ADU to 20000 last night and seem to have a good result. I  will try this setting for a bit just to make sure, Thanks for all the replys.