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Message: <blockquote data-quote="Kevin Purcell" data-source="post: 1529915" data-attributes="member: 68323">Except the Chinese EDs (and the Swaro) all use convergent focussing lenses and have clockwise to infinity focusing. The Leica and Zeiss have divergent focussing lenses and have clockwise to infinity focusing.I think some companies have it in the spec (and perhaps have it in their tradition too).The difference is the matter of which direction your screw thread runs in the rotary to linear motion conversion (assuming you use a screw thread ... IIRC Swaro doesn't have a conventional one but have a patent for a rather clever paddle mechanism). And if the product manager actually thinks to specify the focusing direction. I suspect some don't. Or isn't talked out of it when the engineers tell him clockwise to infinity focusing will need a left handed thread and that'll cost more (or take more effort or limit suppliers or ...).I suspect a few keep it in mind in the spec e.g. I suspect the people who did the basic Chinese ED enclosure and optics design had it in mind (or they got lucky <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" /> 50% chance of that even if they didn't think about it).</blockquote>