Vickers M17 refurb' & modification

[apochronaut]

Those look the same as mine; Complans I would think. The other ones with the smaller eyelens may be the Compens ones. I have seen them on various Vickers units, even Photoplans.

I've had a lot of various Compens eyepieces over the years. Spencer, Bausch & Lomb, Baker, Vickers, Leitz, Reichert. Some unmarked as such but bearing the telltale signature of a yellow diffraction halo.They all seem a bit different , designed to conform to the vagueries of their complementary objectives. Even within the confines of a single manufacturer, eyepieces marked the same can have differing performance so that they keep up with objective tweaks. It's all about having complete freedom from ca at the edge of the field with apochromats. Now that most apos are either fully corrected or obtain final correction in the tube lens, compens eyepieces are a thing of the past.