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Message: <blockquote data-quote="Stephen Prower" data-source="post: 3351755" data-attributes="member: 115634">Russian v Chinese 2.5x17.5 monocularBinastroThe two little Chinese 2.5x17.5 monoculars have arrived.To complete the irruption into CliveP's thread, I report:1. The Chinese monoculars, as the photos in the URLs I gave show, are of a completely different design to the Russian 2.5x17.5 monocular.2. In answer to your particular speculation, the Chinese monoculars incorporate just two lenses, one at the eyepiece end, the other at the objective end.I haven't opened up the Russian monocular to inspect and count lenses.I can't speak re the respective coatings.3. The big difference in specification is the closest focus distance:For the Russian specimen, the distance is 2ft (0.6m).For the Chinese specimens, the distance is 9ft or 14ft (2.7 or 4.3m).As far as I can see from opening up one of the Chinese specimens, the reason for the discrepancy in closest focus distance between them must lie in the distance of separation of their two lenses.4. Otherwise:The Chinese specimens:* Have superior ergnomics to my taste. The attached finger ring is most useful* Give a slightly brighter and more contrasty image to my eyes* Have the above mentioned 'inconsistent assembly' fault* With focus adjustments, give a fully resolved image only out to about 60% of radius* Give a blurred image with marked Chromatic Aberration in the outer 40% of radius.The Russian specimen:* Has, as above, a far superior closest focus distance* Has the previously mentioned irritating, but in practice non-vital, assembly fault of a loose focus mechanism* Gives a more highly magnified image* With focus adjustments, gives not only a fully resolved image out to about 60% of radius, but also a usefully resolved, CA-free, image continuing right out to the edge.5. In short you get what you pay for!The Russian 2.5x17.5 specimen has a full range of utility, and, outside the central zone, usefully performing optics.The Chinese 2.5x17.5 specimens lack both of the above. Nevertheless, by virtue of their equally well resolved central zone, and better ergonomics, they remain potentially useful to clarify and slightly magnify vision out beyond closest focus distance (whatever, given the vagaries of assembly, that distance may happen to be!).Stephen</blockquote>

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