I was looking at the specifications for the new internal focus porro prism binoculars from Minox and Leupold.
The field of view seems restricted in them. I wonder if the internal mechanics of the focuser have anything to do with this? For me a porro with a small field of view is not atractive.
Maybe Nikon will bring us a Nikon EIII 8x30 with internal focusing?
Luca,
It's hard to speculate since neither Leupold nor Minox tells us just how these binoculars are actually focused. The internally focused Kern Focalpin porros from 20-30 years ago used a moving focusing element between the objective and the prism, just like most roof prism binoculars do today. The Canon 10x42 IS L porro uses a moving objective with a protective cover plate like the Swaro 8x30 SLC roof. Neither of these systems should cause the fields to be narrow. The focusing could also possibly be done by moving part of the prism cluster or moving some internal eyepiece elements.
I think the narrowness of the 10x42/44 field is particularly odd. Typically a 10x42 that shares the same body with an 8x42 will have a wider apparent field. It will use a shorter focal length eyepiece, but can use about the same diameter eyepiece fieldstop as the 8x, so a 50 degree AFOV in the 8x becomes 60-65 degrees in the 10x. The 10x eyepiece in these binoculars does appear to have a somewhat shorter focal length than the 8x since its eye relief is shorter. So why isn't its apparent field wider? One suspicion I have is that they are using a simple 3 element eyepiece in both the 8x and the 10x. An eyepiece like that can only produce good results to about 50 degrees of apparent field.