Thanks Terry - I'll give it a shot.
At the weekend I was focussing on learning how to drive the beast with CCDOps. I only have experience with a DSLR and the DSI II using Nebulosity.
I had been reading a chapter in Berry and Burnell (AIP4Win 2.0) on benchtesting a CCD and thought it might be interesting to try out some of the routines adn see how them compare with the published specs. This was the basis of my Dark - Flat, mean of centre and then divide by 60 approach on dark current. While I don't have my workings with me at the office, it looks like your suggestion is a different approach to get to the same result as my tests. I'll certainly look over them this evening.
On another front, I gave it a test drive last night with my LXD-75. I was really trying out focus and testing for internal reflections rather than actually taking decent photos. While I have drop in filters, I have no filter wheel yet.
Initial observations:
1. No filter, no coma corrector - its a v v sensitive camera (compared to the humble 350D). I took a 10 second shot of Orion and found it quite overexposed. I might have tried it out with the screw-in Ha filter I have but time got away from me.
2. Screwed in the MPCC in place of the 2 inch nose piece - I had lots of fun trying to work out the focus and appropriate spacing. Managed that (after a bit). I found that there was some heavy-duty vignetting with my set up. Shots were only 30 seconds and it looks like I took the shots through a tunnel. Will this go away if I move the MPCC further down the spacing tubes? I expect the flats will come into their own now. Perhaps it will be less apparent with filters?
3. Internal reflection - took a shot of Sirius and had a huge internal reflection. I suspect its the scope rather than the CCD as I used to get blue seagulls in the same field with the Canon. Dunno what to do about that.
I have no images to post - they were certainly not up to scratch. perhaps this evening.
Looks like the learning curve is steep. I'd better get the ice pick out and start climbing.
Pete