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Message: <blockquote data-quote="typo" data-source="post: 3439431" data-attributes="member: 83808">James,I'm glad you now understand the crux of the issue.:t: <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" /><img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink    ;)" loading="lazy" data-shortname=";)" />Seriously though, this is something the industry needs to sort out. The ISO standard all of the big companies did allow 'high quality' binoculars to have a full objective resolution that is roughly 2 fold worse than the diffraction limit. If most of that aberration is confined to the peripery of the objective that wouldn't be much of a problem, as that is blocked by the iris of the eye in bright viewing conditions. However if the aberrations were more uniformly distributed then it means that those with 20/15 vision should be able to pick up the problem with poorer samples. You would probably need to be 20/12 or better for the worst of those samples I saw. That's less than 10% of the population. I've now tested a few £200 binoculars that would match the premium models for effective resolution and easily beat those Conquests I tried..I did discuss the problem with one of the senior people at Zeiss a couple of years ago and he assured me they would be developing a new QC protocol, but I don't know if that would cover their binoculars made by third parties.The ISO standard was revised earlier this year. Bizarrely  for 8 and 10x42s the "high quality" limit was actually relaxed to 2.5 times worse than the diffraction limit. Expect more dodgy binoculars in the future.David</blockquote>

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