I did this with the lens stopped down to f/3.5. I actually used a baffle out of a refractor to stop the lens down by placing it inside the lens hood. The iris in the lens causes diffraction spikes on the very bright stars. This time took some care with focusing. Also the fridge by keeping the camera at constant temperature has the added advantage that focus now only changes by factor of about 1/3 with ambient temperature change compared with the uncooled system.
Details
Canon 5DH, Canon 300mm F2.8L at f/3.5. Hutech LPR filter.
Exposures 5x( 1m, 2m. 4m and 8m) at 160 ISO. Fridge at 0.0C. The usual hdr method. I have not used any enhancement. As you can see this is a vast improvement over f/2.8.
Full resolution 4.5MB
http://members.optusnet.com.au/~chee...f3p5%20(1).jpg
Earlier thread here
http://www.iceinspace.com.au/forum/s...ad.php?t=41517
Bert