Asi 224mc and blowing stars

xaralam

Hi !

I have tried some images with the Asi 224mc and always I end up with blowing stars . I used Ascom defaults gain 300 and offset 140 . Is this normal ? For example look at M45 10s x 280 exposures . I use the IR/UV cut filter Baader ccd. I have 2900-3000 ADU in 16 bit mode fits wich corresponding to 3000/16 = 187 Adu in 12 bit .

Sam@ZWO

what scope did you use?

seems focus not very well or bad optics

the star is too large

or the IR-CUT filter didnot work well

xaralam

The above photo was with telelens Pentax SMC 200mm f/4 and the ir filter is the baader L CCD IR/UV cut. I think the problem is the lens or I over exposed the image since with the GSO RC 6 and Asi 224mc and the same filter I don't have the same problem look at the photo below of M76 and NGC891 . I know that the lens from Pentax is not ed and I don't expect excellent results but when I am using it with my ccd SXV-H9 (ccd 285AL sony chip ) and the same filter I don't have same problems. As far as concern focus, in maxim dl I had in M45 FWHM 1.20 on a star in single frame which is pretty good .