DSI Pro and NGC 253

[Aster]

had a go at ngc 253 last night, shot 30 by 30sec frames with envisage but only got a handful of reasonable images.

Question, why do some frames have a darker background then others?
Is that what is called noise?

Attached Thumbnails are
NGC 253 5x30sec stacked in registack curves in Photoshop.

NGC 253-1x30sec-3 untouched
NGC 253-1x30sec-18 untouched

-18 seems to me darker then -3

Would appreciate some advice.

[Lee]

Are you sure the black/white/mid points are set the same for both??? I've found these differences in sets done with the same settings usually due to histogram setting changes.....
Otherwise - not bad for short subs.... 1500mm is a bit long for Sculptor though!

[Aster]

Yes. Took the setting of Auto in envisage and adjusted contrast etc. on the preview to my liking and of I went.

1500mm would'nt be to long with a canon though :)

BTW, just got my reggo for Nebulosity, will give that a go when I figured out how to use it.