Re: gripping an SPL

The bottom of the edge is where the focal point is, the top is where the lens ends. As the focal length of the lens gets shorter, the distance gets shorter also. Longer focus eyepieces have longer top barrels. Unfortunately, this is the result of making all eyepieces parfocal. If we extended the upper barrels and made then longer, we would lose some in-focus. This becomes a problem with binoviewers where little or no in-focus is left. The only other solution is to make them non-parfocal, in which case all the upper barrels can be the same length. I suppose we could add some grooves, but for the really short ones there would be no room left for the lettering. Any other ideas?

Roland Christen

Roland-
Circumferential grooves would help the grip question and could be added to the space between groups of text. The engraved test itself likely offers good grip too. Alternately, lettering could be moved to the conical face and the grooves extended conpletelt aroud the barrel. You might also look into rubberize surface finishes. I know next to nothing about them except that it can be cheap enough to apply to disposable pens.
-Guy

How about a removable fold down rubber eye cup?