Did a test last night and since the Moon was interfering used an Astronomik 13 NM H Alpha filter.
It was also very cold and when I started imaging ambient temperature was 7.2 deg C and at finish 3.2 deg C. I have also mounted a 80mm 0.7 A 12V fan to blow ambient air onto the 5DH. This does drop the internal temperature of the camera by a few degrees and consequently lowers thermal noise.
Large Image 1.6MB
http://members.optusnet.com.au/~avan...EHDR_HA_5C.jpg
Details
Canon 5DH, Canon 300mm F2.8L at f/2.8 and 500ISO, in camera noise reduction (ICNR) ON, 5X( 1M, 2M, 4M, 8M).
Used ImagesPlus to convert from RAW to TIFF and flat corrections and digital development. Then used Registar to median stack each exposure set and produce perfectly aligned versions of each exposure stack which were then processed using EasyHDR to produce a HDR image and then convert to an LDR image. Levels adjusted in PS only red layer used.
This has the result that the bright regions of the nebula are not blown out and the very dim regions show clearly. Noise is almost entirely absent due to the low temperature, ICNR and median stacking.
I am converting a peltier fridge to cool the 5DH so I have more control over camera temperature rather than rely on Melbournes cold clear nights.
Bert