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The Dangerous Alpha aka Lesson Learned. (1 Viewer)

black crow said:
So is the Nikon site wrong with those specs? Are any of the others incorrect? I'd like to know because I own one.
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Yes, the Nikon site is wrong. The real spec is 52 mm. You can measure it yourself! Easiest way is edge to edge rather than center to center of the ocular lenses. I think the other specs for the EII are likely correct, but I have not checked them all.

--AP
 
I just measured my 8X30 EII using my cheap Harbor Freight gauge and got just a "tad" over 52 mm for the minimum IPD. So 52 works for me.
 
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BruceH said:
I just measured my 8X30 EII using my cheap Harbor Freight gauge and got just a "tad" over 52 mm for the minimum IPD. So 52 works for me.
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Well Bruce, my high $$$ precision made Swiss Digital Dial Caliper measured the min IPD at 52.0013 mm. See, like top Alpha Optics, the best tools have the best accuracy!!! 8-P

Wait, I already admitted I returned the EIIs...BUSTED! :-C :brains: 3:)

Ted
 
Theo98 said:
Well Bruce, my high $$$ precision made Swiss Digital Dial Caliper measured the min IPD at 52.0013 mm. See, like top Alpha Optics, the best tools have the best accuracy!!! 8-P

Wait, I already admitted I returned the EIIs...BUSTED! :-C :brains: 3:)

Ted
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Ted .... And here I thought I just learned a "Tad" was equal to .0013mm.

I find it hard to get an extremely precise IPD measurement. I think I am within about plus or minus .5 mm, hopefully a little better. That should be good enough.
 
BruceH said:
Ted .... And here I thought I just learned a "Tad" was equal to .0013mm.

I find it hard to get an extremely precise IPD measurement. I think I am within about plus or minus .5 mm, hopefully a little better. That should be good enough.
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For Sure!!! :t:
 
I had the identical experience with a new Tract Toric 8 x 42, and my initial reaction was very much the same - this is not acceptable and needs to be fixed. To their credit, Tract immediately offered to repair the binocular and sent a postage paid return label. And then a strange thing happened: using the binocular for what I thought was the last time before sending it off for repairs, I realized that I started liking the loose hinge. IPD adjustments were a snap, I very easily found the widest view and it never slowed me down enough to miss a bird. I am not suggesting that I would want to loosen the hinge on all my binoculars, but the Tract Toric works for me and I think it's certainly worth giving your loose hinge a chance.
 
I have the same issue with my Kowa Genesis. At first I was dismayed but with use I've found the exact same thing you have. I prefer it and it really doesn't slow me down. I often start to open them as I bring them toward my eyes and often I'm right there where I need to be by the time they land on my eyes, or I'm very close and need only a tiny adjustment.
 
black crow said:
With my bins when using very close focus I'm always adjusting that.
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BC
By all means continue to do this if it makes viewing more comfortable but it isn't necessary in this sense. Both of your eyes receive an image of your close up subject and the only thing that is really odd is that you see two circles of field of view that only overlap to a limited extent. But if you experiment by concentrating on the image of the subject as you close the IPD up a bit you will find that although you bring the two circles into a closer overlap, the actual image doesn't really change. What this means is that if you can learn to concentrate on the image and ignore the 'not overlapping circles of view' you will find that you don't need to mess about changing the IPD narrower and wider depending on viewing distance.

It feels kind of odd at first but I found it gets easier with practice. However I shouldn't sound too smug about this as I mostly can't do that trick of viewing through a scope with both eyes open. Sometimes I can but mostly I can't.

Try it out and just remember to concentrate on the subject and don't keep looking at the partly overlapping fields of view.

Lee
 
I will. Where I notice this the most is with the porro binoculars. Not so much with the roof even with very close focus.

It's pretty interesting and something I hadn't considered much at all when thinking about optical experience is how much the brain is involved in what and how I see things.

This quote below was a something I found beyond fascinating. And got me thinking of other things like how one sees the size of the moon high up in the sky vs along the horizon.
The greater parallax of porro binoculars means that the image of an object at short or medium distance will get closer to the medial parts of the FOV of each tube, compared to a roof binocular (or reverse-porro) where the object will be shown more towards the center of the FOV.
When the object appears to the left in the right tube, and to the right in the left tube, you must converge more with your eyes to not experience diplopia (double-vision).

So what goes on here?
When you converge with your eyes, your brain will recalculate the object size. It will appear smaller and closer.
It is easy to show this perceptual phenomenon with a weak prism from the trial lens kit.
With one eye closed, the prism will only move the image sidewards. No change of the apparent object size will happen, since the prism has no dioptric power.

With both eyes open and the prism base facing laterally, the eyeballs are forced to converge and the object will appear smaller. With the prism base facing nasally (and this may only be possible at shorter viewing distance), the eyeballs can converge less than without the prism, and the object will seem bigger.
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At first I had trouble believing it until I tested it out. Also can you explain why I never have to adjust the Pentax Papilio very close focus binocular? It's alway got that perfect circle no matter how close or far.
 
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black crow said:
At first I had trouble believing it until I tested it out. Also can you explain why I never have to adjust the Pentax Papilio very close focus binocular? It's alway got that perfect circle no matter how close or far.
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The Papilios are "reverse porros", with objectives that are closer than their ocular IPD's!

Ted
 
black crow said:
It's pretty interesting and something I hadn't considered much at all when thinking about optical experience is how much the brain is involved in what and how I see things.

At first I had trouble believing it until I tested it out. Also can you explain why I never have to adjust the Pentax Papilio very close focus binocular? It's alway got that perfect circle no matter how close or far.
Click to expand...

1 Remember: the simple lens in your eye throws an image on your retina that is upside down. And yet you see the world right way up without a set of Schmitt Pechan prisms inserted in your eyeballs. Your brain learns which way is up and presents you with a properly 'right-way-up' image. So right from the get-go your brain is interpreting what you see.

2 Ted is right about the Papillios.

Lee
 
Troubador said:
1 Remember: the simple lens in your eye throws an image on your retina that is upside down. And yet you see the world right way up without a set of Schmitt Pechan prisms inserted in your eyeballs.
Click to expand...

This isn't just some correction the brain applies in this case, it's how it basically works. The more amazing thing is that if you could put something like that in a newborn's eye, they would learn to see just fine with their retinal image rightside up, and never know a difference. That's a neural network for you. Look at some of the devices they come up with today as aids for the blind. The same principle applies to AI image recognition and other computer "learning" too.
 
tenex said:
This isn't just some correction the brain applies in this case, it's how it basically works. The more amazing thing is that if you could put something like that in a newborn's eye, they would learn to see just fine with their retinal image rightside up, and never know a difference. That's a neural network for you. Look at some of the devices they come up with today as aids for the blind. The same principle applies to AI image recognition and other computer "learning" too.
Click to expand...

A couple of years ago I read of the case of man who had a most extraordinary vision problem. Cutting a very long story short his vision had a hole in it where no image was formed and around it was a normal image. His brain could not tolerate this hole and so searched his memory and inserted images from his memory into the hole. Mostly these inserted images were of stained-glass windows positioned high up in churches in a position that corresponded with the hole in his vision. Of course this meant he had a stained glass window in his vision all the time no matter what he was looking at. I can't remember for sure how this was cured but I think he had some surgery and he recovered some vision to fill the hole and the images of the stained-glass window disappeared.

Lee
 
Wow! That's trippy. I wish I had a user manual for my brain. I'll bet it can do a lot more than we think. It's just waiting for us to wake it up.
 
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