You'll just love my 10",full aperture,water filled prism+grating, once it gets finished. I tried the prototype on a 6", seems ok
-------------------- Jc
ATM 10" F6.1, 1/25th wave spec (max wavefront error +/- 1/12.6 in zone 4 of 6, sodium light )
6" F7 spec
127mm F9.4 Refractor
10 x 50 bin
ETX80 (finder)
Canon 20D
and a curious mind