Try before you buy! There is remarkably quite a variation in how these things are put together even though our two eyes are pretty much laid out he same on all of us. But some may prefer how the eyepeices "fit" us with Leica, others on Zeiss, others with Swaro. Cleyspy at Cley in Norfolk has a six hundred yards back garden so you can try ALL of those makes and many others plus used binoculars out to that long distance. Standing in the middle of Mount Street outside the Leica shop, or in Hall B at the NEC at the Swaro stand at the British Shooting Show will only give you a limited distance to view. Other vendors, however such as Garlands may be based in the countryside (like Cleyspy) and again have a long back garden!
Also some binoculars will focus down very close others not so close. On my old Leica 7x42 BA Trinovid they wouldn't focus down as near as my son's Leica 7x42 Ultravid HD. Yet that's sixteen feet close in vs ten feet which only for watching butterflies might be relevant? For must users including myself it wasn't.
Bigger isn't better. It's just offering something that may be useful or may not be useful. The lower the magnification the wider the field of view and, more importantly, the longer in distance the depth of field. That's say that with 7x magnification what's in front of what I want to INITIALLY examine and what's behind it will be in focus to a further distance in front and behind that with 10x magnification. That can be important in helping you assess what you then decide to do next.
Personally? As I've posted elsewhere I much prefer 7x but only because nobody in quality stuff makes 6x! Only Leica today of the German makers makes a company 7x42 which is something offered neither by Zeiss nor by Swarovski.
Last but not least...if relevant...check the waterproof quality of each maker's product, its spares and repairs back up and, finally, its weight and general "handiness". I loved my Leica 7x42 Trinovid BA but they weighed much more at 890 grams than do my son's 770 grams Leica 7x42 Ultravid HD. Optically though you'd be hard put to tell them apart in normal use.
There's an America website called "AllBinos" -
www.allbinos.com - just select REVIEWS that has a easy multichoice drop down review facility of two hundred binoculars for an easy to find way to check the technical specification. Or you can cheat that review box by entering, say, Leica 7x42 Trinovid BA allbinos in Google and it'll bring up ALL the AllBinos review facility that way.
