Interesting.
Everything I am reading says to make that number MUCH smaller ie .05 or even 0 when using a 50mm guide scope.
I can see the logic of making it smaller as a larger move on a 50mm guidescope translates to a VERY large move on a 1000mm focal length main scope.
I guess its a balancing act between making this number small but not too small to cause oscillation.
See craigs starks post on this here:
http://www.cloudynights.com/ubbarchi...sed/sb/5/o/all
Here is what he said
"Well, I've guided with an 8x50 finderscope and am the author of PHD
http://www.cloudynights.com/ubbthrea...lins/smile.gif
The trick is that you need to drop the minimum pixel motion parameter way down. For most (reasonable, non-insane) guide setups, the default of 0.25 pixels works well. If you're on a very short setup, this may correspond to a few pixels on your image rig. I run this at 0.05 when using the guide scope as the guider.
The M27 and M57 shots near the top here were done on just such a rig:
http://picasaweb.google.com/celstark/Astrophotos
Craig "