Very strange issue with vignetting

Posted by: @tsk1979

typical flat frame via NINA Flatwizard

Please show a screenshot with autostretch off. The peak should be in the center without applying any stretch at all.

Posted by: @tsk1979

Typical darkflat. I will upload the frames on upload server too, but wondering whats going on? 

Your darkflat isn't evenly lit. The center is brighter than the corners. This indicates a light leak in your system.

HTH, Wouter

https://upload.astropixelprocessor.com/index.cgi?launchApp=SYNO.SDS.App.FileStation3.Instance&launchParam=openfile%3D%252FAstroPixelProcessorUpload%252Ftanveer%2520flatissue%252F

unstretched - also updated sample lights, darkflats and flats.

I will discard my dark flats I have never used them before and flats have been enough usually.

But even thought dark flats. I get the same result

@tsk1979 Why is that upload.astropixelprocessor.com URL in that otherwise empty comment?

The unstretched flat looks good to me.

In order to perform correct flat calibration, APP requires flats and either dark flats or bias. So please make sure you use those. Note that the temperature, exposure time, gain and offset of the dark flats need to match those of the flats. If the exposure time doesn't, APP requires bias frames as well of the same temperature, gain and offset as the flats.

Hi 

Those are my flats. I took flats again. And now problem is gone. I needed Bias and darks I guess. Did not need to take darkflat at all

Final stack is looking good. Now will run this through the post processing steps like star reduction after I gather some more data on this target