Tonight I tried the new William Optics ZenithStar 66 SD apo refractor - thought I'm using it as a guide scope. It did a great job and has a nice focal length at 388mm to guide the 800mm focal length R200SS.
In order to use the DSI with it I needed to either use a long extension tube or a star diagonal. Tonight I tried the diagonal, I'll try the extension tube next time.
Something that I found surprising was that the stars were quite dim compared to using the finder as a guide scope. I think this may be due to 2 things:
1) The f ratio of the finder is f/4 or so and the ZS66D is f/5.9
2) I was using a very cheap star diagonal which is likely losing some light
*UPDATE* I pulled the diagonal and went with an extension tube and the stars were immediately brighter. Cheap diagonals cause significant light loss.
So I'll need to continue to play with the settings and configuration until I really have it dialed in.
The moon was 3/4 full tonight, but in my test of the new guider and what guide settings work best with it, I shot M51 while I did so.
The clouds were coming and going and I only took 8 dark frames for 16 light frames (not a good ratio!) so the image is pretty poor, but it's here and I'm posting it anyway.
Scope: Vixen R200SS 200mm @ f/4 w/Baader MPCC
Mount: Orion Sirius EQ-G with GoTo
Guiding: Meade DSI Pro and PHD Guiding
Guide Scope: William Optics ZenithStar 66 SD
Camera: Canon EOS 20D (unmodified)
Special Settings: None
Exposure: 48 minutes - (16 x 180s)
Processing Software: Acquired in Nebulosity, Stacked in Deep Sky Stacker, Levels and Curves in Photoshop
See Gallery below for image