Re: Review of TMB Super Monos with Valery on board

From: Edward (reply_at_thegropup.thx)
Date: 06/28/04 

Date: Mon, 28 Jun 2004 03:41:43 GMT

"MrGrytt" <mrgrytt@ix.netcom.com> wrote in message
>
> How is anything I said a "stretch"?

The monocentrics, when proper executed, are certainly fine planetary
eyepieces. However, some of the exuberance about them is more akin to team
sport than optical science. There is no such consensus on the optimal
design and much less agreement on the real world implementation. I admire
TMB and his work, I just cringe when people are compelled to declare
superiority without sufficient basis, whether it is AP, TMB or ETC.

Roland Christen posted the following on AP-UG, which I will repeat here,
simply to muddy the waters a bit and perhaps allow once again for some
diversity of thought.

" While talking with Thomas Baader several years ago about eyepiece designs,
we discussed the original Zeiss monocentric vs. the newer Abbe Orthoscopic
designed by Dr. Pudenz of Zeiss Jena. It was quite clear from the spot
diagrams provided by Pudenz that the Abbe Ortho was quite superior in
off-axis corrections (Zeiss has all the original data for all their old
designs, as well as samples for testing). In fact, when Zeiss originally
designed the APQ line of triplet refractors, much thought was given to a
suitable planetary eyepiece set for these refractors. According to Baader,
the designers at Zeiss did look at a modern version of the monocentric, but
even with the highest index and most modern glasses, they were not able to
achieve equal performance to the Abbe Orthos. The only way to do it was to
use an aspheric surface on one of the elements, something that could be
practical at 20mm or longer, but would be prohibitive at shorter focal
ratios." [R. Christen]

Regards,
Ed T.

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