Thought I'd start this thread off to ask about folks experiances of porro prism binoculars and (in my opinion) their only downfall as far as design is concerned..namely the bridge piece!!
I'm currently using an Opticron TGA 7x42, these have an excellent bright and very sharp image but because of the amount of movement of the focusing mechanism image quality is greatly affected by what direction I am focusing from, ie if I focus from near to far one of the barrels will be out of focus compared the the other..focusing from far to near and the problem seems to be resolved but as you can imagine this is far from ideal!!
From handling different models of porro's from different makers there seems to be a great deal of variation in the movement..or lack of in the bridge despite the fact that most of the budget models (excluding Swift and Nikon)look identical and probably originate from the same factory?
Matt
Matt, that very problem was the main reason I switched to internal focussing roof prisms a good many years ago. I too had major grief with the barrels becoming 'out of sync', usually when I'd taken the focus to the extreme and was bringing the barrels back 'in'. I had several pairs of porro prisms, indeed there are 4 pairs in the loft now gathering dust.
I've never noticed that problem with my Nikon Es or SEs. It does turn up in lesser bins, though.