This is a DSLR "Work-in-Progress", and also an exercise in theory meets practice.
I have been experimenting with different ISO settings on my uncooled 400D in an attempt to find an optimum, and (being the nerdy type that I am) thought the best way to settle it would be to conduct an experiment. Firstly run a series of darks at different temps and plot SNR vs exposure time for different ISOs and temperatures (as per Roger Clark's methods
here). Graphs are relative to the noise of my 400D at 300s ISO800 and 20 degrees C (the plot for 20C is not shown here)
To my surprise ISO1600 came up trumps, so it was time to test with something challenging. I decided NGC4038 - The Antennae.
The data I have so far was taken over two nights using my VC200L with focal reducer - this is a HDR combine in Pixinsight of 67 x 180s ISO1600 subs (ambient temps of about 10-14C) and 53 x 240s ISO1600 subs (ambient temps of about 8-13C). Hi res version here:
http://www.astrobin.com/full/40743/?mod=none
Am hoping to add to this over the next few imaging sessions, but I thought the process of determining exposure time might be of interest to some. And of course any advice or comments on my image capture and processing is also very welcome. The balance between the background and extended galaxy arms in particular I found quite challenging. I plan to post some updated images when I have collected some more data.
Thanks for looking
