hello.
After many years birdwatching in many different habitats worldwide I found that the perfect spec's for a single pair of bins for me was around 7x50 with at least an 8 degree field of view, fairly close focus, waterproof, rugged. Porro or roof doesn't matter. (Apparently only the top roofs match the good prisms)Reasonable eye relief (I dont wear glasses) ie above 15mm, reasonable exit pupil ie 5mm or above. Not too heavy. Obviously I also want good crisp true colour optics. Anyway No-one as far as I know manufactures bins with these specs!! HELP!!
By the way magnification for me was a tricky one but 7x with wide angle field of view means I can pick birds up very quickly particularly those close in. vital in rain forest or forest thicket type habitats. I pretty much carry my scope with me all the time I bird (incidentally 30x WA 80 mm objective) so I really don't need a higher mag. So what is out there that's close?
Zeiss : Classic 7x42 bgatp: these famous bins have well known pros and cons
the major cons for me are small objective lens ideally, not fully waterproof or nitrogen filled (although apparently rare to experience problems)
Leica: 7x42 cons (again small objective lens) and a marginally small FOV than ideal. I have a pair of 10x42's and although excellent optically FOV isn't great.
(note: a 50mm objective lens has approx 50% greater light transmission than 42mm so Im not just being picky)
Swarovski: none as far as I know have a decent field of view
Alpen (optolyth): optically good (i have a pair of 10x 50) but even if they met the Ideal specs I just dont like using them.
Pentax: I havent tried their 7x 50's but they're not WA and not close focus (I dont know how good optically good their porros are.
Bushnell: they actually do a pair of 7x 50's (WA even), however I haven't even looked at them as they do I'm sure for the price a less than accurate 'perma focus'. I did own a pair of bushnell 8x42 wa that were super value for money (nice to use).
Opticron: visited their 'headquarters' recently and although optically very good, none really fitted my ideal specs. However even though I didn't get on with it, the 'Aspheric' model must be a serious contender for best value for money.
Swift Audubon: Only looked at the 8.5x44 820 model - Excellent pair of binoculars-superb clarity throughout the FOV I found only marginal difference between the ED and regular version - however dodgy eye cups, too high a magnification ideally and again too small an objective lens
Nikon - supposed to have the sharpest image of all bins but no model 'fits the bill'
For me It has to be between zeiss classic 7x42 BGAT, Leica 7X42 BN and the Swift Audubon 820 8.5x44.
note: The Zeiss night owl 7x45 version Is too heavy + I don't think it has a large FOV
Any helpful comments are appreciated particularly if there is a 7x50 WA out there thats decent optically etc..
Wide angle 7X50's can only be done properly by using very large and heavy prisms and eyepieces. That is because an aerial image with a real field of 8+ degrees at the focal plane of the typical f/3.6-f/4 50mm objective is too large for conventional sized prism apertures and eyepiece field stops. There is a new Miyauchi 7X50 WA. If you can find a photo of it you will see just how huge such a binocular has to be. Inexpensive offerings, such as might be available from Bushnell will probably simply ignore the design requirements which results in excessive vignetting of the aperture.
I can't say I see anything much to be gained from a 7mm exit pupil binocular for birding. The extra light gathering over a 6mm exit pupil is only realized when the eye's pupil is open to more than 6mm which requires virtually total darkness. Have you tried the new Zeiss 7X42 FL. I believe the 7X42 BGAT* has been discontinued.
Henry
I know this may not be exactly what you are looking for but for a wide field of view you might want to check out the Nikon 8x30 EII
I know its an 8 power but at 461 ft FOV it has a wider fielf than any 7 power that you listed
Leica 7x42 BN 420 ft
Leica 7x 42 BR 420 ft
Zeiss 7x42 BGAT 450 ft
Zeiss 7x42 FL 450 ft
Swift 8.5 x 44 430 ft
Its also very light at just over 20 oz, very well reveiwed in BVD and Alula and alos conveniently under $300.
Just something to consider