Estimating that a standard 12.5" blank with a chamfered edge can have about 12.4" clear aperture, here's a really nice f/6 system for Ed and everyone. No cemented doublets, just a pair of single meniscus lenses in a cell with an airspace ring, and a practical, shallow hyperboloid primary only 17.7% deeper than the equivalent paraboloid. This is unusually nice and shallow; most Rosin primaries want to be in the 200% correction range.
The N-PSK3 and fused silica glass blanks should be readily available in H3-H4 quality. 3" BFL should be plenty for CCD/filter cameras as well as DSLR's like the 60Da. Axial imagery is sharp enough for high-power visual work, the field is within a few percent of DL over a 1" diameter, and the corrected spectral band is from 0.4-0.9 microns, suitable for any CCD's and DSLR's without giving image bloat. The diagonal is a standard 3.0" minor axis, with a lateral offset of 0.106" away from the focuser and toward the primary.