With such beautiful clear cold conditions last night I got out the old 300..f2.8 lens from Bert and did Eta Carina. The lens has a handy filter holder in the back that takes 2 inch filters so used a UV/IR and LPS filter. I also used a f3.5 aperture stop in front of the lens as it stops unwanted light entering the lens where the internal iris cannot. Modded 350D camera. 7 x 5 mins ISO 200.
Tracking was easy with an 80mm guidescope. Manually guided by keeping a guidestar on a virtual reticle on the laptop. I also dithered each frame by moving a number of pixels in different directions after each exposure. Calibrated and processed in Iris, finished off in Photoshop.
full res. version here.
http://d1355990.i49.quadrahosting.co...lear12degc.jpg
Scott