Call me crazy, but I’m seriously thinking of getting myself a 40mm Rodenstock eyepiece. Before I commit, I’m hoping that folks who have (or have had) this eyepiece can answer a couple of questions for me:
1) Does this eyepiece actually have a field stop and, if so, is it sharp?
The cutaway diagram of the eyepiece on the BW-Optik website does not show a field stop, whereas Chris Lord, in his “Unusual Eyepieces” document states that the eyepiece has a sharp field stop. (I have found no other references to the field stop in my searches.) Is anyone able to help with resolving this contradiction? Chris, if you’re reading this, I would love to have your input.
2) What kind of coatings does this eyepiece have?
BW-Optik describes the coatings as multilayer. Everyone else (including Chris Lord) says that they are single layer. And apparently the eye lens is uncoated on its outer surface.
Clearly, I am hoping that, with regard to Question 1, BW-Optik is wrong and that, with regard to Question 2, BW-Optik is correct.
The field stop issue is a potential deal-breaker. The coating issue is, in comparison, quite minor — I find that, at large exit pupils, differences in transmission are not as noticeable as they are at small exit pupils.