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Message: <blockquote data-quote="henry link" data-source="post: 3367834" data-attributes="member: 6806">O-N,I’m pressed for time, so I can only give a short general response for now. My overall takeaway from your response is that you, also, have found no independent corroboration for your belief that aspherical elements are present in old Japanese binoculars. I’m sure you realize that you are the one and only person making such a claim, so I’m afraid the onus is on you to do the work to prove it. I think you’ll need to provide more persuasive evidence than just your personal impressions of what you see when you look at lens reflections.  My skepticism about this comes from following a history of posts in which your unproven ideas on various topics have been represented as established facts. Many times, however, your ideas are demonstrably wrong. One handy example is the quote below from your last response, which I’ve also seen repeated in several other posts.“An Erfle basically has a Barlow section up front. As that moves, you get different trade-offs….”That reads to me like a simple statement of fact about how Erfles work. The problem is that it’s not true. Erfles do not have a “Barlow section up front”. The field doublet is positive, the exact opposite of a Barlow. A quick look at any ray trace diagram of an Erfle will demonstrate that. If the field group is negative like a Barlow then the field stop of the eyepiece will be located behind it, not in front of it as in an Erfle. A quick look at ray traces of eyepieces that do have Barlows up front will show that. Presumably this misunderstanding is where your notion of the “stretched Erfle” comes from. Whatever it is, an eyepiece with a negative field doublet widely separated from a positive singlet and doublet is not an Erfle, stretched or otherwise.I’ve looked at many cutaways and disassembled a fair number of eyepieces. What I’ve seen in old binoculars (with a few exceptions) appear to be variations on three types: Kellner, Konig and Erfle. I’d be interested to see photos of the odd types you report finding to see if I think they could fit into one of those families. Apparently, you and I can look at the same eyepiece and reach different conclusions about it. For instance, where I see ordinary spherical surfaces in the field doublets of the Rangemaster and my Tower 7x35 EWA you see aspherical surfaces, and contemporary Zeiss eyepieces don’t look to me like they “defy an easy placement in the old styles”. They look like four and five element Konig variants, except for the SF, which has been described as an Erfle combined with a field flattener.I could go on but that’s all the time I have for now. Probably the best response would have been to just remind you of Carl Sagan’s famous challenge to overreaching theorizers: “Extraordinary claims require extraordinary evidence”.You’ve made many extraordinary claims. Now let’s see the extraordinary evidence.Henry</blockquote>

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