If you check out the Peterson Eyeopener page there is a link to a chart that lists the usability of different focal length eyepieces with different objective sized scopes.
This is the 8" chart
http://www.petersonengineering.com/s...8_inch_SCT.htm
And this is the 10"
http://www.petersonengineering.com/s...0_inch_SCT.htm
The 9.25 is in the middle I guess
