eitanaltman
Well-known member
Since we are talking about wide FOV (and at this point many/most premium 8x32/42 binoculars have a FOV as wide, or wider, than that of the 7x35 or 7x42 Leicas) this reminded me of something relevant to the question earlier about why there are so many 7x fans, which I don't think is discussed enough.
When people discuss FOV/focus it's nearly always in terms of AREA, as in "what percentage of a (flat) circle is visible and sharp?". It's all about "sharp to the edge". I don't think enough attention is paid to the VOLUME of space that is clear and in focus, which is a function of both FOV and DOF..... as well as the field curvature.
Everyone judges edge blur by staring at something flat and seeing how sharp the stuff is at the edge. The text at the edge is blurry! But the world is 3D, not 2D. I don't use binoculars to read text on a flat sign, I'm using them to observe the natural world.
If you reframe the discussion as "what % of the VOLUME of 3D space is in focus?" instead of "what % of the AREA of 2D plane is in focus?" the 7x42 UV suddenly leaps ahead of the flat field 8x42's.
When you gaze out at the natural world, which is not flat and does not have sharp edges, the curved field 7x42 UV shows more of that world as clear and in focus than the flat field 8x42. Whereas the flat field 8x42 presents more like a plane of focus "slicing" through the landscape, the curved field 7x42 UV produces a big "blob" of focus. And, precisely because of the field curvature, the edges of the "focus blob" sort of bend towards you (like a jelly bean lol).
This is my horrific 30 second effort in MS Paint to represent what I mean visually. Pretend this is an overhead view, the green oval is the zone of clear focus for the flat field 8x42, the orange "jelly bean blob" is the area of clear focus of the 7x42 UV:
If you're looking at a flat subject (like a sign with printed text or a piece of graph paper) to test "edge sharpness", the green oval presents as much "better" than the orange jelly bean. My Nikon EDG 8x42 would get a higher score than the 7x42 UV in the "edge sharpness" category. But if that's a bird perched on a big shrub, with bushes and trees and ground and all sorts of other stuff around and in front / behind the bird, more of that natural space is clear and in focus with the orange jelly bean.
Or per the water discussion above, flat field fans will point out how that storm petrel which flitters into the edge of the FOV will be more in focus.... but what about the bird 50 feet behind the subject bird? or 50 feet in front of and to the left?
I think this is a big part of the "magic" of the 7x42 UV -- if you stop focusing on just the edges, there's just so much stuff that is clear and in focus! Some people like that "slicing" effect and how it isolates the subject in focus more. But for my preferences, the 7x42 UV feels more "natural" and "transparent" than anything else I've used and I've concluded it's largely because it feels the most like you're NOT using an optic, because it more closely approximates normal vision.
But not just any binocular can pull this trick off. I've used plenty of other 6x-7x binoculars and none of them do it at the level the 7x42 UV does (I haven't had the pleasure of using the 7x42 FL, so I don't doubt that it has similar appeal in this respect). It's this magical chemistry of huge sweet spot, huge FOV, great glass, perfect sharpness, that great Leica color and contrast, the lower magnification, the curved field....
When people discuss FOV/focus it's nearly always in terms of AREA, as in "what percentage of a (flat) circle is visible and sharp?". It's all about "sharp to the edge". I don't think enough attention is paid to the VOLUME of space that is clear and in focus, which is a function of both FOV and DOF..... as well as the field curvature.
Everyone judges edge blur by staring at something flat and seeing how sharp the stuff is at the edge. The text at the edge is blurry! But the world is 3D, not 2D. I don't use binoculars to read text on a flat sign, I'm using them to observe the natural world.
If you reframe the discussion as "what % of the VOLUME of 3D space is in focus?" instead of "what % of the AREA of 2D plane is in focus?" the 7x42 UV suddenly leaps ahead of the flat field 8x42's.
When you gaze out at the natural world, which is not flat and does not have sharp edges, the curved field 7x42 UV shows more of that world as clear and in focus than the flat field 8x42. Whereas the flat field 8x42 presents more like a plane of focus "slicing" through the landscape, the curved field 7x42 UV produces a big "blob" of focus. And, precisely because of the field curvature, the edges of the "focus blob" sort of bend towards you (like a jelly bean lol).
This is my horrific 30 second effort in MS Paint to represent what I mean visually. Pretend this is an overhead view, the green oval is the zone of clear focus for the flat field 8x42, the orange "jelly bean blob" is the area of clear focus of the 7x42 UV:
If you're looking at a flat subject (like a sign with printed text or a piece of graph paper) to test "edge sharpness", the green oval presents as much "better" than the orange jelly bean. My Nikon EDG 8x42 would get a higher score than the 7x42 UV in the "edge sharpness" category. But if that's a bird perched on a big shrub, with bushes and trees and ground and all sorts of other stuff around and in front / behind the bird, more of that natural space is clear and in focus with the orange jelly bean.
Or per the water discussion above, flat field fans will point out how that storm petrel which flitters into the edge of the FOV will be more in focus.... but what about the bird 50 feet behind the subject bird? or 50 feet in front of and to the left?
I think this is a big part of the "magic" of the 7x42 UV -- if you stop focusing on just the edges, there's just so much stuff that is clear and in focus! Some people like that "slicing" effect and how it isolates the subject in focus more. But for my preferences, the 7x42 UV feels more "natural" and "transparent" than anything else I've used and I've concluded it's largely because it feels the most like you're NOT using an optic, because it more closely approximates normal vision.
But not just any binocular can pull this trick off. I've used plenty of other 6x-7x binoculars and none of them do it at the level the 7x42 UV does (I haven't had the pleasure of using the 7x42 FL, so I don't doubt that it has similar appeal in this respect). It's this magical chemistry of huge sweet spot, huge FOV, great glass, perfect sharpness, that great Leica color and contrast, the lower magnification, the curved field....
I think some claim that edge sharpness increases apparent FOV but I'm afraid that I don't buy that (or rather, it doesn't work like that for me), and when it comes at the cost of having a relatively two dimensional image instead of an immersive three dimensional image..... well I know which I'd rather have......
