Thanks for the reply David.
Personally I usually want 17mm or more to be satisfied. However, the true important factor is the useful eye relief. Some binoculars have unnecessary recessed ocular lenses which results in that you loose several mm of the eye relief. For example Fujinon 10x50 FMTR-SX: despite a HUGE ocular lens with a long eye relief of 20mm the useful eye relief is ~12mm if I recall correct. It could be great for eyeglasses if the eye lens wouldn't be recessed WAY to much! That glass had been mine since several years if the ocular design had not been so stupid.
Another thing I am disappointed at is that the manufacturer's pictures of binoculars mostoften don't show the ocular lens. It can be several pictures in different angles from the side and of the objective, but no picture of the ocular. That's sad because there is hardly of interest to see the objective lens. But if I see a picture of the eye lens with eye cups downfolded that is more valuable than a stated eye relief in mm. Actually I can usually know if the (useful)eye relief is adequate for my needs by seeing such a picture!
Personally I usually want 17mm or more to be satisfied. However, the true important factor is the useful eye relief. Some binoculars have unnecessary recessed ocular lenses which results in that you loose several mm of the eye relief. For example Fujinon 10x50 FMTR-SX: despite a HUGE ocular lens with a long eye relief of 20mm the useful eye relief is ~12mm if I recall correct. It could be great for eyeglasses if the eye lens wouldn't be recessed WAY to much! That glass had been mine since several years if the ocular design had not been so stupid.
Another thing I am disappointed at is that the manufacturer's pictures of binoculars mostoften don't show the ocular lens. It can be several pictures in different angles from the side and of the objective, but no picture of the ocular. That's sad because there is hardly of interest to see the objective lens. But if I see a picture of the eye lens with eye cups downfolded that is more valuable than a stated eye relief in mm. Actually I can usually know if the (useful)eye relief is adequate for my needs by seeing such a picture!
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