I have a B&L 10-mm "Orthoscopic" where the field very
much looks the part.....no 'hula-dancing' at all in the distant tree trunks.
It is a 1,2 (Konig type 1, "reverse Kellner"). It is a 47-deg afov.
Contrast is very slightly shy of the mark, though.
"Orthoscopic" is a term that is not exclusive to the Abbe, for sure.
An ES 52-degree complies with that flatness better than an Abbe...it seems.
The OP says....does cropping a Plossl view down to 40 degrees afov
make it 'more orthoscopic'. Yes...it must, necessarily.
By a lack of physical warpage, it certainly does.
Mathematically, quantitatively, cutting-the-core-out-of-the-watermellon, yes.
It is just 40 degrees.
The RKE (1,2) is the only EP to back it up,
by specifying the geometric errors. That is a 43 degree field.
The question for me has always been....contrast.
The Abbe design is especially good at shedding stray light.
A Plossl choked to 40 degrees would do well, but you might
need a thinner blackened iris than card stock. Or edge-tapered.
Edited by MartinPond, 29 November 2020 - 03:37 PM.