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Edge to edge sharpness - a misleading criterion? (1 Viewer)
- Thread starter John Cantelo
- Start date
WJC
Well-known member
R U nutz!? These days, I couldn't afford a picture of one. I will have to slum by with my 8x32 SE.
This is God getting me back for all the material things I ONCE owned . . . but never will, again.
Bill
Pinewood
New York correspondent
Hello Chosun,...
A lot of my 'birding' is done by detection of movement - in the outer field that doesn't need tack sharpness, but enough to be able to detect movement. I didn't think that the Swift sufferred that much (given it's $2.5K view for less than 1/5 that cost!, until one day when I was lakeside and could hear Rainbow Bee-Eaters ......... low and behold upon recentering the bin, there had been one perched on a dead branch, sitting reasonably still apart from the beak, in that outer 20% of the field --- didn't notice him at all in the blurred Swift edge !!! Now I want 'enough' sharpness in that outer field to be able to detect and process stationary targets .....
I don't have to have the field tack sharp to the edge (especially at 70° AFOV -which is impossible to look at from the fixed central gaze anyway - and somewhat risky too - I believe if the wind changes while you're doing that, then you'll stay cross-eyed like that forever - at least that's what my dad told me! |
Chosun :gh:
Target acquisition, in bird watching, certainly encompasses motion detection. I would add that colour and mass detection are useful on the periphery, as well. In all three, one can acquire a new target with some softness, at the edge. How much softness in a wide FOV, is probably a personal preference.
Happy bird watching,
Arthur Pinewood :hi:
Chosun Juan
Given to Fly
Hello Arthur, Bill, Bruce, Mark, and all others!
Yes, not only a personal preference - but an individual capability as well - everyone's accommodation will be different.
My position (which miraculously agrees with just about all that has been written above!
is that my peripheral vision is not perfectly sharp (as I suspect goes for everyone - mutants excepted :eek!: so the sharper the view to the edge the better - PROVIDED - that:-1) No "rings" of softness are introduced somewhere to the rest of the field.
2) Excessive AMD is not introduced to achieve it (by that I mean that a smoothly transitioning distortion profile that would be no more than around the k~0.7 value, which should suit most people - naturally Mr Magoo, and probably Brock :scribe: too won't be entirely happy
3) Designers should strive for a well corrected field approaching 70° AFOV.
4) This should not come at the expense of light weight, high transmission, or sufficient eye relief (18mm+) - which is probably going to neccessitate a pretty fancy design, and not just a little expense ......
5) Optical designers should also try to include some very slight 'sense' of field curvature and pincushioning to enhance the 3D effect sadly lacking in roof prism designs.
6) This could be tailored for different target markets - with flatter views provided to the lower exit pupil diameter designs, which are more likely to be used by those who have seen the back end of middle age and are headed for the 3 score and ten mark .....
7) Among other design parameters! ......
Chosun :gh:
Kammerdiner
Well-known member
I'd be surprised if that were the case. "Individual capability"? I've never been accused of that before, especially not in the eyeball department. Thanks, CJ!
But I had this thought. My accomodation is basically zero, at least it seems that way to me. That might explain why I like a flat field. Because my eyes can't do anything about curvature. Of course in the FL it's mostly astigmatism so nobody can do anything about that.
Still, I'd be rather surprised if people couldn't "perceive" the difference between, say, the Zen ED2 and the Zen Prime in terms of edge sharpness, even staring straight ahead. Thoughts from all concerned?
And Bill I have to think the SE edges have something to do with why you use it, yes? Even though the SE blacks out about as quick as any binocular I've ever used. I think I once described the 8x32 SE as having a "godlike calm" to the view and I'm pretty sure the edges played a role in that.
Mark
perterra
Well-known member
I'd be surprised if that were the case. "Individual capability"? I've never been accused of that before, especially not in the eyeball department. Thanks, CJ!
But I had this thought. My accomodation is basically zero, at least it seems that way to me. That might explain why I like a flat field. Because my eyes can't do anything about curvature. Of course in the FL it's mostly astigmatism so nobody can do anything about that.
Still, I'd be rather surprised if people couldn't "perceive" the difference between, say, the Zen ED2 and the Zen Prime in terms of edge sharpness, even staring straight ahead. Thoughts from all concerned?
And Bill I have to think the SE edges have something to do with why you use it, yes? Even though the SE blacks out about as quick as any binocular I've ever used. I think I once described the 8x32 SE as having a "godlike calm" to the view and I'm pretty sure the edges played a role in that.
Mark
In my opinion once you start wearing glasses everything changes, if you are wearing progressives and you have a pretty agressive prescription then the only sharpness you will see anytime is within the zone of your glasses you are looking through at the time, upper left is going to focus different middle left, middle left different than lower left. So unless your prescrip is the same as mine, you wont see anything the same, binocs or not
jaymoynihan
Corvus brachyrhynchos watcher
Actually no. It is only in focus on the point you are concentrating on. It does scan very fast and constantly when your eyes are open though, and your brain knits a coherent view.
I think a flat fov or sharp edge to edge is very important in a binoculat that will also be used in astronomy. I also prefer a flat fov when starring for a long time at one place or group of birds, if i am behavior watching, so i can scan around the field with equal quality of view.
WJC
Well-known member
I'd be surprised if that were the case. "Individual capability"? I've never been accused of that before, especially not in the eyeball department. Thanks, CJ!
But I had this thought. My accomodation is basically zero, at least it seems that way to me. That might explain why I like a flat field. Because my eyes can't do anything about curvature. Of course in the FL it's mostly astigmatism so nobody can do anything about that.
Still, I'd be rather surprised if people couldn't "perceive" the difference between, say, the Zen ED2 and the Zen Prime in terms of edge sharpness, even staring straight ahead. Thoughts from all concerned?
And Bill I have to think the SE edges have something to do with why you use it, yes? Even though the SE blacks out about as quick as any binocular I've ever used. I think I once described the 8x32 SE as having a "godlike calm" to the view and I'm pretty sure the edges played a role in that.
Mark
Hi Mark:
The SE blacks out because some people don't know the eyepoint; if they did, it wouldn't.
As a younger man, I would search and search the skies for Andromeda—usually unsuccessfully for many minutes. Now, even on nights of poor seeing, I can throw the bino to my face and there it is. Over time, I learned it’s position relative to the surrounding constellations. That made all the difference.
The eye relief is always at the same place. It doesn't change because we don't know where it is. Yet, if we learn where it is, and can hold the bino still, there's no problem.
And, as I have said, given all a simple test to prove for themselves, and had many others back me up on, human peripheral vision is NOT sharp. That has been shown medically, scientifically, and proven here. I don't anticipate the argument, strong opinions, and speculations going away. I just anticipate being burned at the stake for putting people down by standing by physiological realities.
Bill
Alexis Powell
Natural history enthusiast
To those interested in this issue, and in clear discussions on the topic, I ask: How much of the fall-off in human vision from the center to the edge (fovea to macula to other parts of retina) has to do with attaining proper focus versus the resolving ability of those parts of the retina? It is my understanding that the difference in _focus_ to the fovea versus the rest of the retina is trivial. More important are differences in _acuity_ owing to photoreceptor density, photoreceptor type (cone versus rod) and the related issue of the ratio of receptors to ganglion cells (the latter of which determine the resolution of shape perception), and the degree to which ganglion and bipolar cells overlie the photoreceptors (as in most of the retina) or not (as in in the fovea). If that is the case, it is still proper and relevant to speak of whether a binocular delivers a sharp (focused) image to one's extra-macular (including peripheral) visual field. Also, if the difference in focal length to the fovea and rest of the retina is trivial, then the binoculars that do best for providing the best image possible to our peripheral vision may also be those that appear sharpest at the edges when examined with our foveal vision when looking around the view (off-axis). In my experience, that is the case, so flat-field bins such as the SV (or, when using bins to scan open places, those that have field curvature that closely matches the difference in distance to the foreground and the center of the field) provide a superior view.
--AP
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Kammerdiner
Well-known member
Oh I know where the SE eyepoint is, Bill. I had to roll the cups down exactly halfway to get to it with my glasses. But in my experience it was a fussy eyepoint compared to the 8x32 SV. What do they call it? Spherical aberration of the exit pupil I think. Definitely not a roam around view in my experience.
And of couse I never said peripheral vision was sharp. I know it's not, but all I need to do to prove that having things sharper in the periphery is noticable is to put my glasses on.
Mark
And of couse I never said peripheral vision was sharp. I know it's not, but all I need to do to prove that having things sharper in the periphery is noticable is to put my glasses on.
Mark
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WJC
Well-known member
Hi Mark:
I don't doubt that YOU do, but so many others don't. Optics is a foreign subject often explained by sales material, hyperbole, and speculation.
I sold an SE to a customer at Captain's, who returned about a week later complaining of the blackouts.
He explained that he had bought the bino on my recommendation. He had asked what I used for birding, and made a snap judgement. His philosophy was that light goes in the front, comes out the back, and that he shouldn't have to, "chase it to get a good 'picture'."
Had he been willing to spend just another 15 minutes in the showroom, all that and more would have been covered. I offered my customers much more than a bino in a box. But, as with hundreds of other times, this customer didn't have time to be bothered with realities. After all: what is there to know about binoculars?
So, the customer didn't KNOW, didn't have time to know, and I had to take it in the shorts because of it.
Cheers,
Bill
The 8x32 SE is a beautiful binocular but unusable for me due to blackouts. I have to hold it away from my eyes which is totally impractical for birding. The SE will suit some eyeglass wearers, and not others, depending on the design of their glasses, and the shape of their face.
Vespobuteo
Well-known member
I guess depth of field (DOF) should be equally important, in many situations, probably why I prefer lower mag binoculars.
But looking at something very near or very far is completely different scenarios. When chasing warblers close by, complete edge to edge sharpness is not important, on long distance, scanning wast areas, fuzzy edges can be disturbing, and I think it's the fuzzy edges per se, that are the problem, not the size of the FOV, fuzziness is an anomaly, anomalies is disturbing, but of course it's a matter of balance, my 7x42 FL:s edges are a bit too fuzzy on the long range, but for closer subjects, I don't notice it, and the big FOV and DOF if probably more useful in those cases.
But looking at something very near or very far is completely different scenarios. When chasing warblers close by, complete edge to edge sharpness is not important, on long distance, scanning wast areas, fuzzy edges can be disturbing, and I think it's the fuzzy edges per se, that are the problem, not the size of the FOV, fuzziness is an anomaly, anomalies is disturbing, but of course it's a matter of balance, my 7x42 FL:s edges are a bit too fuzzy on the long range, but for closer subjects, I don't notice it, and the big FOV and DOF if probably more useful in those cases.
kkokkolis
Περίεργο&#
No it isn't. Sweet spot was invented by mammalians and it is called fovea.
If I have to choose then: wide & sharp > wide & fuzzy > narrow & sharp > narrow & fuzzy > absolutely nothing at all. And of course, marginally fuzzy > quite fuzzy > very fuzzy > Mr Magoo. And big sweet spot > small sweet spot. And my daughter's University studies > another optic in the inventory.
It is so complicated!
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bh46118
Well-known member
WJC
Well-known member
Hi Leif:
The glasses add a new dimension to the problem. I were glasses, but NOT when bird watching. Which is about over for me for the season. We had a good summer, but last night I pulled out the electric blanket.
Bill
Alexis Powell
Natural history enthusiast
Ah, but maybe you shouldn't have
Your use of the word sharp was ambiguous. Often, by sharp, the concern relates more to focus than to resolution. Following my post #50, I like to read your statement as follows (even though I know it wasn't the original intent):
Human vision achieves sharp focus to the edge, so maybe a good binocular should also.
--AP
WJC
Well-known member
Ah, but maybe you shouldn't have
Your use of the word sharp was ambiguous. Often, by sharp, the concern relates more to focus than to resolution. Following my post #50, I like to read your statement as follows (even though I know it wasn't the original intent):
Human vision achieves sharp focus to the edge, so maybe a good binocular should also.
--AP
But words are relative, people are relative, conditions are relative.
Over on the astronomy side of observing, you will see people talking about their Schmidt Cassegrain providing them with "tack sharp" images, when you KNOW that's not true. They use that phrase because they believe it is supposed to be desirable. In such a centrally obstructed system, it can't be. But, if you KNOW that, and say so, you're a ______________, fill in the blank.
Photographically, the point is well proven. A star cluster may have "tack sharp" stars in a 6-inch APO, but the same photo taken with an 8-inch SCT will look like something doctored with Crayolas.
The truth does not bend to whims or a lack of understanding.
Bill |=)|
kkokkolis
Περίεργο&#
I quoted before I had the chance to read all the thread, sorry.
