Tom, Byron - Here is the simple RC prescription we talked about the other
day.  It is pretty arbitrary:  4-meter (so we can use the KPNO tank) f/1.57
primary, f/15 system EFR.  

M1: 4000 mm diameter, 12560 mm radius of curvature, -1.01074 conic const.
M2: ~750 mm diameter, 2665.6 mm radius of curvature, -1.98391 conic const.
Separation M1-M2:  5156.44 mm (vertex to vertex).
Back focal distance (M1 vertex to focus) 2000 mm.

The details shouldn't we worried about.  This is intended to be a generic
RC for the purpose of costing. - Ted
