> This begs a question - since the Nagler designs there have been no
> further significant advancements in the eyepiece state of the art. What
> is next?
Cheaper eyepieces with the same performance ?
On the same topic, apart from MEADE's copycats (which are almost as expensive and bulky as Naglers), there is another eyepiece on the market with supposedly same excellent edge-to-edge performance, but smaller, lighter and cheaper. It is sold under various names, but the most common is Widescan. I even saw the excerpt from a Japanese magazine praising it and giving it better marks that "two other competing eyepieces" (Nagler and Meade ?). Anyone has any experience with those ?
> I have an old WWII Zeiss 90
> degree field binocular objective that uses only four elements (supposedly,
> the eye lens has an aspheric surface). It performs about like an Erfle
> at the edge of the field (but is 90 degrees vs the 70 degree Erfle
> I am comparing it to). Why can't someone mass-produce an aspheric
> eyepiece?
Because it is very difficult to mass-product aspherics. Nikon has now improved the technique of some sort of controlled vacuum depositing, but it's only useful for largeish elements (camera lenses, several cm in diameter), and it's really only useable for very mild aspherics. I understand that aspheric reversed orthoscopic has a very steep curve.
Bratislav