Thanks for the quick reply, Art. That agrees with my research...but for fairly short exposures (under 30 seconds), the tracking appears to be adequate. That's why I'm concerned about image brightness.
Also, you stole my avatar! In other forums to which I subscribe, I've always used good old Charlie Brown. Looks like I'll have to find a different one for this forum. :-) Craig
-------------------- Craig
Ancient Tasco 4.5" (from back when Tasco's were good)
Meade ETX-80
Orion XT10i
Meade Super Plossls 6.4, 9.7, 15 & 26mm
Zhumell Z Planetary 3mm
Agena Ultra Wide 30mm