OK I'm an old film guy and a newbe to DSLR AP
Here is where Im' at:
Canon 450D unmodified
Mirror lock up set
Auto Dark frame set
Manual mode (bulb)
remote shutter cable
Tamron 400mm F4 lens with drop in 420NM filter
From a red Zone
Using live view to focus.
Results: I'm getting nice round tiny star images with no trailing but my exposures are limited to about 12 seconds before the histogram moves right of 1/3
Back to my question , Is there anything else I need to do or should do before taking multiple exposures to stack?