asi 183 MM Pro - terrible flats at Ha

Hello,

In good faith I bought an ASi 183 MMPro and wanted to take Ha pictures with it.

But if I use a Ha filter, 3.5nm or 7nm, there is strong vignette in the flats as well as in the recordings.

This is NOT due to the telescope, the image field is illuminated for full format.

This is not the case in the normal spectrum.

please here, a normal light source, a sheet of paper, no optics and no filter

and here with a asi 533

Hi Stefan,

This situation is normal, you can calibrate the vignette by flat.