Whatever the arguments about 3D effect and ergonomic it's important to remember that porros typically have fewer optical surfaces over which light can be reflected and lost or (worse still) bounced back to create haze. Porro prisms rely on total internal reflection in their prisms so don't require the passing light at different angles on semi-silvered surfaces that require phase-correction coatings and other such hi-tech wizardry (like some roof designs). For very simple physical reasons they should be brighter. I have a second hand pair of Zeiss Dialyt's and I miss the cheapo porros (Bushnell 8x42 natureviews, less than 100 quid!) I had before them which were optically superior in every regard, massive field of view, pin sharp and mega bright. I don't think this discussion should be about individual models but it goes to show that pound for pound porros are better. The Fujinon 7x50s porros are reputed to have a light transmission of 95%, I think this is the highest of any production binoculars. I would like to see a return to a porro based market and suspect that manufacturers feel they can justify higher prices for more complex designs so most of them don't push the boundaries with the inately superior porro design fo fear of undercutting themselves.
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