[NorthernLight (Max)]

me again,

last night the weather here improved so dramatically that I had clear skies until almost 3am.
Everything worked perfect after I hooked the whole shebang to the laptop, so I could sit back, relax and enjoy a nice bottle of shiraz.

I chose the sculptor galaxy and decided to push the limits and expose for 10min. To my suprise I found today that after I stacked them all in Deepskystacker the resulting image was completely white and featureless. Tweaking around in Photoshop helped the situation but I am sure that I have totally overexposed the images (vigetting was awefull too). See below the best I could do so far.

So what is the key for correct exposures and how do you determine the amount of shots to be stacked?

Shot details:
150mm f5 newton
Canon 450D no filters
8x10min
no darks, no flats, no bias (was so excited that I forgot about it)
Median Combined in Deepskystacker
PS CS2: levels, curves, crop, downsample (for posting here)

Your guidance is as always much appreciated.

Cheers!