Posted By Ed Zarenski
Check back with Cory to confirm your discussion. The difference in coatings, if all surfaces are coated MgF vs FMC will be substantially more than 10%. The difference in lost reflected light can be 0.5% per surface coated vs 4% per surface uncoated. There can be up to 14 surfaces in a binocular.
I tested and published results on Oberwerk models that were FMC vs Oberwerk that had MC on Objectives but only MgF on prisms and eyepieces. I recorded differences of several tenths of a magnitude in Limiting Magnitude, differences in amount of faint diffuse light that could be seen and noted significantly greater ghost images in the nonFMC version.
Personally I recommend to all my forum visitors on CN that if budget allows then do NOT purchase nonFMC binoculars.
An 8x56 binocular is a special condition binocular. Most users will never be able to use it to the full potential of its aperture because it has a 7mm exit pupil. Two reasons that's not a wise choice follow.
For a person with eye pupils that dilate to only 5mm or 6mm, that 8x56 will be an effective aperture of 40mm or 48mm, not 56mm. Few people can utilize a 7mm exit pupil. I recommend if their eyes can only dilate to 6mm don't get anything larger than an exit pupil of 6mm.
In moderately light poluted skies of around mag 4.0 to mag 5.0. it will do no better than an 8x40 binocular. A larger exit pupil binocular in poor skies has such washed out images that it performs no better than a much smaller binocular. I recorded data to show this relation and published the results from a comparison of Fujinon 10x70 vs Fujinon 16x70.
So my point about 8x56 being such a special condition binocular is this; it needs to be matched to eyes that can fully utilize the large exit pupils and it needs to be used under very dark skies to prevent the washed out effect. Personally, I would place an 8x56 uncoated binocular on the shelf right next to my 30 year old 7x35 Sears $29.95 binoculars. That would be precariously close to the trash bin. Single coated is a bit better.
My suggestions, go with fully multi coated throughout to pass more light and eliminate internal reflections and go with the 11x56 for the 5.1mm exit pupil, an exit pupil that can be utilized by a broader user group.