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Michael,
In relation to your guiding question ,the following is the Astro Imaging setup I used for both objects.
1. 960 mm ED127 Refractor
2. Skywatcher AZ-EQ6 Mount
3. Celestron OAG
4. PHD2 - Locally modified.
5. Guide Camera - QHY5L-II
6. Guide duration - 3 seconds
Given the fact that I had a good polar alignment and my gear was well balanced , I believe I was able to achieve the 20 minute guides as a result of the modifications I made to PHD2. Prior to the mods I was only able to get passable 10 minute guides. Nobody ever questions the guiding software but blames everything else for bad guides. To me PHD2 seems to overcorrect forcing one to play with a multitude of interacting parameters to correct the over correction.
I made two modifications to PHD2
1. I binned the guide image from 1280*960 to 640*480 . The effect of this is to sharpen the guide stars which tends to help PHD2 as it appears to like nice round definite guide stars.
2. I modified the guide exposure time , so the round trip time of guide exposures matched the setting in the PHD2 dialog. It is interesting to note that a guide exposure of 1 sec with the QHY5L-II takes approximately 1.25 seconds. This additional time represents one quarter of the exposure time.
Cheers
Rob
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