Field of veiw 8x32 v 8x42 (1 Viewer)

Hello all, i was just pondering as to why there is usually a wider field of view on the smaller binoculars e.g. the 8x32's I would have thought that the larger objective 8x42's would be wider. Also is there then, more advantage in buying the smaller ones for general bird and wildlife watching, due to the wider view.

Phil.

Hi Phil,
It's probably a priceing factor. Good wide angle eyepieces cost more to make than standard eyepieces. As a general statement, the eyepieces in 42mm binoculars have longer focal lengths than those with equivalent power have in 32mm binoculars. And those eyepieces in quality binoculars will cost more.

I like to use binoculars with a wide FOV. Especially at close to medium range distances. I think they are easier to use. I can pick up the object viewed faster. But a difference of 30 or 40 feet in the FOV at 1000 yards doesn't seem to me to be very significant. A difference of 80 to 100 feet does, however, make a big difference.

Cordially,
Bob

I had the same question. presumably 8x32 and 8x42 by the same maker are of the same quality, so why doesn't 8x42 offer the same wide FOV that 8x32 does.

Hello Bob, thanks for your reply and explanation...i understand the difference better now.

Regards,Phil

Only two things determine the width of the real FOV in a binocular: the focal length of the objective and the diameter of the eyepiece fieldstop. The typical 8x32 has the advantage over a similar design 8x42 because its objective focal length is almost certainly shorter and its eyepiece fieldstop is likely to be about the same size. The shorter focal length objective of the 8x32 forms a smaller image at the eyepiece fieldstop than the 8x42 objective. The smaller "picture" at the objective focal plane in the 8x32 naturally produces a wider image field within the same fieldstop diameter. Achieving the same real field in an 8x42 with a longer focal length objective means increasing the size of the eyepiece fieldstop, which in turn requires larger eyepieces and larger prisms to prevent vignetting.