Hi Guys,
I read about typical flat frames should be a bright ball with darkened corners or edges because of the vignetting. But in my case, it is so weird that the dark edges is only comes in the bottom to the right of the image, and it's not evenly circular like a vignette.
Do you know what cause this? When the flats is applied to light frames, the image is getting worst than before it was flat fielded
And I notice a horizontal darker lines on the very top of the image. Is there something problem with the sensor?