[ausastronomer (John Bambury)]

Scott,

Nice survey.

You could have expanded the "sharpness" criteria to "on-axis" and "EOF" as two separate items IMO, to make it a little more complete. Specifically for the reason that "on-axis" sharpness is the single most important criteria to me but off axis sharpness, particularly near the EOF is not such a major concern.

In addition, three other criteria you could include would be.

1) lack of off axis astigmatism.
2) lack of rectilinear distortion
3) Ability to cope with a steep light cone, ie to work in a fast F-ratio telescope

I opted for the same four criteria as Lee and in no particular order.

Sharpness
Contrast
Light Transmission
Eye-Relief

CS- John B