Off the Beaten track - NGC1893

Hi all, I decided to try and learn a litle more using my William optics 110 flt scope and Canon 40D in early January. Starcluster NGC1893 is a nice object in Auriga with some nice neblosity in it along with a distinct 'hole' in it's centre. This is catologued at magnitude 7.5, and 25 arcminutes in size, so I though it would be a good test for the scope.

I shot at ISO1600, with a stack of 49 light frames, and 10 darks at 90 seconds each unguided, plus 5 flat and bias frames, although I am still being killed by vignetting. I know the colour balance is a little off, but I am learning at snail's pace due to all the recent cold weather and not being able to get out....

Does anybody have a great tip for the vignetting, what am I doing wrong?? Thanks.

www.flickr.com/photos/79652716@N00/5364925324/

Keith..

Keith - that's a nice image. Keep at it and it'll pay off.

As regards vignetting, I really don't see any in the posted image (unless you cropped the offending areas). My only suggestion would be flat frames. I'd suggest five is a bit low. Perhaps 10 or even 20 would be better.

Don't forget - the flats are "divided" into the light frames.

One other note, if your darks are the same exposure duration as your lights, you don't need to use a bias frame. Bias frames are handy if you dark exposure duration does *not* match your light exposure duration...


HTH

Dave

I was going to suggest Pixinsight LE which was a free download and great at getting rid of vignetting but they have pulled the download from the Pleiades Astrophoto S.L. site. I guess too many people were using the freeware and not buying.

Thats is very good Keith. Dave is right you must get flats This would be Ideal for the 110mm

Have a look here this is the road I went down and works great

www.themcdonalds.net/~themcdo/richard/in..._Light_Box_for_SV80S

Carl

Nice image Keith, focus looks to be a little bit of an issue or maybe that's just me? Some nice nebulosity all the same.

Seanie.

Ah thanks guys for taking the time to reply, I'll definitely work on the flats, and i'll use no bias frames so, that's ok! I did crop the frame to remove most of the vignetting, so it doesn't look as bad there.

Pity about the pixinsight, oh well thanks for the tip Kieran and the link Carl, I'll follow it up. As for the focus, yes Seanie, the stars look a little large due to the processing, but overall I am happy with this so far.

Looking forward to dragging the CGE mount out again since my set up is portable

Keith..