I use the spreadsheet below to help me decide on eyepieces.
Just put your scope dimensions in to the two pink boxes, diameter and focal length in millimeters, and it gives you various data for all the eyepieces I've gathered the specs for.
Here's what the columns mean:
Size: Focuser tube diameter in inches (2 inch, or 1.25 inch)
FL: Focal length of the eyepiece
Mag: Magnification of that eyepiece in your telescope
Exit Pupil: Self explanatory
Light Gath: The relative amount of light in the eyepiece of your telescope
App field: The apparent field of the eyepiece as stated by the manufacturer
Real Field: The field of view in arc-minutes using that eyepiece in your scope
Relief: Eye relief as stated by the manufacturer
Field stop: The eyepiece field stop as stated by the manufacturer
Real field is the one I look at most, then balance that up against the magnification.
The green section at the top is just where I copy the specs for the eyepieces I actually have, to give something to compare the others against.
OK, I can't attach a .xls file, so it's posted here:
http://www.deepdiving.net/misc/eyepieces.xls
Cheers,
Jason.