ATM erect image finder

[Ajay Talwar <ajayt@del2.vsnl.net.in>]

hi all

just wondering whether erect image can be obtained in a finder.

Consider the following statictics
Objective
        Dia     : 50mm
        f.l.    : 200mm
Eyepiece
        f.l.    : 8mm

What lenses (diameter and focal length) are to be introduced to produce an
erect image in such a system.
Are there any formulae for calculating the final magnification, fov etc
for such a system.

I want to avoid using prisms.

Thank you in advance for any responses

Ajay Talwar