Fujinon had better change the info page on their website then, as it mentions "field flattener lenses" no less than eight times...
Regarding the question asked in the original post: if a binocular is advertised as having field flatteners I'd expect it to have good, if not excellent, edge sharpness, as that's been the case with pretty much every such binocular I've tried. I can't offer an opinion on the Meade and Celestron products mentioned, though, not having tried them.
I like a large "sweet spot" and good edge performance in my binoculars, but who doesn't? Although I suppose it isn't absolutely critical for the image to be sharp to the very edge (unless the field of view is somewhat narrow), if it is, so much the better - from my point of view anyway. I know motion can register in my peripheral vision even if it's not sharp, but the sharper the image is across the field of view, the better overall awareness I feel I have. I feel really good edge sharpness can to some extent make up for a smaller field of view.
The diagram in Wikipedia (appreciate it's Wikipedia, but...) shows about 80 degrees of vision that ought to be reasonably sharp. I'd estimate that at least 60 degrees of my own vision (the 18 degree arc of my "macular vision" and around two thirds of the 30 degrees of "near peripheral" vision to the left and right of the "macular vision" arc) is pretty sharp. I like the so-called "sweet spot" of my binoculars to correspond to that, and ideally exceed it. The Nikon 10x42 SE I own, with about 60 degrees apparent field of view, sharp to the edge, just about accomplishes this, I wouldn't like to go any narrower.
Regarding the question asked in the original post: if a binocular is advertised as having field flatteners I'd expect it to have good, if not excellent, edge sharpness, as that's been the case with pretty much every such binocular I've tried. I can't offer an opinion on the Meade and Celestron products mentioned, though, not having tried them.
I like a large "sweet spot" and good edge performance in my binoculars, but who doesn't? Although I suppose it isn't absolutely critical for the image to be sharp to the very edge (unless the field of view is somewhat narrow), if it is, so much the better - from my point of view anyway. I know motion can register in my peripheral vision even if it's not sharp, but the sharper the image is across the field of view, the better overall awareness I feel I have. I feel really good edge sharpness can to some extent make up for a smaller field of view.
The diagram in Wikipedia (appreciate it's Wikipedia, but...) shows about 80 degrees of vision that ought to be reasonably sharp. I'd estimate that at least 60 degrees of my own vision (the 18 degree arc of my "macular vision" and around two thirds of the 30 degrees of "near peripheral" vision to the left and right of the "macular vision" arc) is pretty sharp. I like the so-called "sweet spot" of my binoculars to correspond to that, and ideally exceed it. The Nikon 10x42 SE I own, with about 60 degrees apparent field of view, sharp to the edge, just about accomplishes this, I wouldn't like to go any narrower.
