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As others have said... Expose longer... If the skyglow is a problem, either get a Hutech IDAS LPS filter, or take plenty of shorter subs... I would say 5min is the minimum exposure time for any target out there (apart from M42 which always requires some short subs to tone it down a bit) when I'm at dark skies, I don't bother with anything less than a 20 minute exposure, unless im capturing colour information for a Ha lum or something like that. with an LPS, 10min subs should be doable from suburban skies... I would strongly recommend doing this over taking heaps of 3 min subs...
As Robin and Gary said, the gain and offset can be different for every camera, Gary's was Gain 1 Offset 114.. My QHY8 was Gain 1 Offset 66... So follow that guide that Robin linked...
Also, with a 16bit CCD, you can expect to have to do quite a few itterations of levels and curves to pull out data... Unless you're taking very long subs, the data will not be clearly visible in an unprocessed image like it is with a DSLR.... It will only be clearly visible in 15~30 minute subs without applying some stretching...
I have an unprocessed 30x20min shot of M8 and M20 on the HDD, I can upload a JPG copy of how it looks pre-processing for you to show you what I mean... even with the epic exposure times, its still not much to look at...
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