looksharp65
Well-known member
Sorry about the title. After 15 minutes of thinking, I could not come up with anything better.
So guys (Henry, Kevin, Frank, Steve et al), I would like to ask you a couple of things that are a bit puzzling to me.
Let's begin with apparent field of view. We all know how to compute it roughly by multiplicating the magnification with the true field of view. And I am a big AFOV fan. A big AFOV provides a "Wow!" experience and simplifies the targeting.
I can't really see the need for pinsharp edges if the downside is a narrow TFOV/AFOV.
Anyway, it is not a secret that a couple of my bins have an AFOV of about 56 degrees. I would have wanted more but I can handle it.
The thing is, I use eyeglasses most of the time, and occasionally contacts.
When using glasses, and the eyecups are down, I have a feeling that the AFOV is greater. Of course it is not, but the "Wow!" comes when using glasses. When eyecups are extracted, and that wide black rim surrounds the image, I somehow get a feeling of tunnel vision. And reversely, when the eyecups are retracted so the rim appears thinner, the field seems to widen.
This leads me to thinking, if the ocular ends of the binocular's barrels are as thin as possible, and the exit pupil as large as possible, and the eye-relief generous, the "Wow!" experience would be granted. The "real AFOV" is easy to compute, but does it necessarily express what the perceived vision through a given binocular is like?
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The other thing I would like to make a comment upon is about the speed of the focusing knob. Here and elsewhere, it is defined in terms of "one and a half rotation from closest focus to infinity".
The problem with this generalization is that binoculars have different closest focus. And the closer, the close end of the knob rotation needs increasingly more space.
My Minox is a fast-focuser with only one full rotation from close to infinity, but it takes a few "jumps" with the finger to reach infinity. (The depth-of-field is quite shallow in this model)
But my Vortex can focus a lot closer, and needs something like 1,25 rotations from closest to infinity. Its depth-of-field is tremendeous however, so in real use, I rarely move the knob more than about 50 degrees, which is easy to do without "jumping" with the index finger.
I believe that a more veracious description of focusing speed would be obtained if we settled for a close focus of 3 m/10 ft, and then how many degrees of turning it takes to get the first sharp focus on infinity. That is, for binoculars with deep depth-of-field, when focused to the hyperfocal distance.
For binoculars with shallow DOF, it will take more turns to reach infinity.
The eyesight, pupil size and age of the individual tester will probably make some difference here but I guess the results could be made quite reliable if there is a reference binocular involved in the game.
Waiting for your gathered wisdom to comment upon this.
Kind regards
/L
So guys (Henry, Kevin, Frank, Steve et al), I would like to ask you a couple of things that are a bit puzzling to me.
Let's begin with apparent field of view. We all know how to compute it roughly by multiplicating the magnification with the true field of view. And I am a big AFOV fan. A big AFOV provides a "Wow!" experience and simplifies the targeting.
I can't really see the need for pinsharp edges if the downside is a narrow TFOV/AFOV.
Anyway, it is not a secret that a couple of my bins have an AFOV of about 56 degrees. I would have wanted more but I can handle it.
The thing is, I use eyeglasses most of the time, and occasionally contacts.
When using glasses, and the eyecups are down, I have a feeling that the AFOV is greater. Of course it is not, but the "Wow!" comes when using glasses. When eyecups are extracted, and that wide black rim surrounds the image, I somehow get a feeling of tunnel vision. And reversely, when the eyecups are retracted so the rim appears thinner, the field seems to widen.
This leads me to thinking, if the ocular ends of the binocular's barrels are as thin as possible, and the exit pupil as large as possible, and the eye-relief generous, the "Wow!" experience would be granted. The "real AFOV" is easy to compute, but does it necessarily express what the perceived vision through a given binocular is like?
-----------------------------
The other thing I would like to make a comment upon is about the speed of the focusing knob. Here and elsewhere, it is defined in terms of "one and a half rotation from closest focus to infinity".
The problem with this generalization is that binoculars have different closest focus. And the closer, the close end of the knob rotation needs increasingly more space.
My Minox is a fast-focuser with only one full rotation from close to infinity, but it takes a few "jumps" with the finger to reach infinity. (The depth-of-field is quite shallow in this model)
But my Vortex can focus a lot closer, and needs something like 1,25 rotations from closest to infinity. Its depth-of-field is tremendeous however, so in real use, I rarely move the knob more than about 50 degrees, which is easy to do without "jumping" with the index finger.
I believe that a more veracious description of focusing speed would be obtained if we settled for a close focus of 3 m/10 ft, and then how many degrees of turning it takes to get the first sharp focus on infinity. That is, for binoculars with deep depth-of-field, when focused to the hyperfocal distance.
For binoculars with shallow DOF, it will take more turns to reach infinity.
The eyesight, pupil size and age of the individual tester will probably make some difference here but I guess the results could be made quite reliable if there is a reference binocular involved in the game.
Waiting for your gathered wisdom to comment upon this.
Kind regards
/L