[APML] Re:

[Aplanatic@aol.com]

Gil:

Here's the design of the 14.5" f/7.65 RC:

Primary: D=14.5" RoC=77.43" SC=-1.11
Secondary: Spacing=25.625" RoC=40.1" SC=-5.46

BFL=12"

Field Curvature: RoC=14.4"

If you don't use a field flattener and have a flat film surface, at 1.5" off-axis the RMS spot diameter is about 165 microns and the vignetting is 23% due mostly to the primary baffle.

If you use a well designed field flattener that also cancels some of the astigmatism, the RMS spot diameter becomes about 35 microns at the same off-axis distance as above.  The vignetting in this configuration is about 20%.  The distance from the rear lens to the focal plane is about 3.5" in this design, but could be increased if you require it to be so.  The EFL of the corrected design is about 118", i.e., has an f/ratio of f/8.13.

The lenses are 3" in diameter and the curves, and tolerances on the curves and lens thicknesses, are easily achieved.

Do you need it?  Well, that's entirely up to you.  But I will say that this well corrected RC for medium format film photography would be quite an instrument.

If you would like the design, I can type it out or send it in OSLO LT format.

Dave Rowe





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