Hi Frank,
very nice setup you have!
Looks like your tracking is working well.
But... and as Simon pointed out, your back ground is way to dark.
Ok, first things first, you don't need to take darks with that chip... the Sony chips are relatively noiseless... use a sigma combine method and the noise disappears.
Don't worry about any flats for the time being unless you really need to do so.
The data doesn't appear to be stretched at all as I can gather bringing it into Photoshop. With 108 minutes of data, this image should be well illuminated showing a great deal of information and detail to both the object and the background (stars, faint & bright and small fuzzies).
What image acquisition and processing program are you using??
I suspect if you're using the Atik program, you need to do some reading on how to stretch the data correctly. I believe this program works well, but I have never used it so can't comment.
With what you have, go back to your original raw images and have another try at stretching each individual sub then combine them with a sigma filter.
I think you'll be impressed.
Nice image and nice to see an image from the TSA120.
Galaxy imaging is a bit of a stretch for any refractor really unless 7 or 10 inches in aperture. Event then mirrored scopes do a better job usually.
Focus may be a tad off and its hard to nail it exactly without an electronic focuser although it usually just means a bit more work with the microfocuser and trial and error.
A great cheapish electronic focuser is the Robofocus.
NGC 4631 with the TSA 120 & 314L+
