Flat Field question:

From what I've read about taking flat frames, is that the optical path must not be changed from imaging an object to taking a flat frame (focus, orientation of the camera).

So, how do you do that? It's 1:00am, I'm done taking my images, then I put a T-shirt over the end of the scope and point a lightsource at it then take the flat frames?

Should this be done at the end of every session?

How are these flat frames applied to the actual astro images?

???

Set the scope up:

Checked Collimation, aligned, focusing with eyepiece para focal to my DSI, Adjusted anti-backlash settings, Found my guide star, inserted camera, imaged this.

Jay's knowledge and information really helped me process this one much better than the last.

No vignetting in the image this time. I used my OIII filter, which might have eliminated vignetting. 

I decided not to use flat frames and just keep my optics clean and use at least a pollution filter.

Those two things will let me sneak by without taking flat frames, at least for now.

When I get a wedge and go for longer exposures, vignetting may become more of an issue. 

Anyway, I'm happy with my results...

Nice result!  Congrats!

 Thanks for all your help!

 IMHO, that is a pretty tought object to work with. Starting on something with less stars to deal with will be easier.

Russ