I have certainly been inspired by Humayun's images when he was doing the 40D posts last year (and still my favourite is his Orion shot with the 200mm F2.8L) and Doug yes that 200mm lense is a very nice unit. With a cheap and old mount like the LXD55, it doesn't allow the 200mm to really shine but will certainly work on this.
Doug and H thanks very much for your info and that image of Phil's I believe won a David Malin award? For now, I will stick with the 50mm and get the mount tracking nice. I'm almost there so my next step will be to try going out to around 5 minutes for a start.
Couple of questions though:
1. I've seen the more seasoned guys use a method called "dithering" which I understand is a way to slightly vary each frame for improved stacking. Would this be of any benefit with DSLR imaging?
2. A DSLR sensor's temp will always change over the night. Would one recommend taking a light -> dark -> light etc or light -> light ->.. then dark -> dark ->. To me it seems mathematically more accurate to do light-dark-light-dark etc.
Cheers, and thanks. Your work Humayun has kept me to push on to get the best out of my equipment. A G-11 is on my radar once I am happy I have full confidence in my gear & capabilities. I have used a G-11 very recently with the new Gemini 2 (it's a bit tacky compared to Autostar) and compared to the LXD55, I had sweat starting to drip on my credit card
Darrin...