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Discontinuous 3D effect (1 Viewer)
- Thread starter Ted Y.
- Start date
WJC
Well-known member
Hi, Ted,
It has NOTHING to do with the type of binocular. I assume by “branches” you are referring to “barrels” or, more correctly, TELESCOPES. The 3-D “effect” is a product of looking at a target from TWO POINTS OF VIEW ... each telescope has a slightly different point of view. The farther the telescopes are separated, the greater the effect. At 30 feet, it can be great; at 200 yards it can be ZERO. I’ve worked on 27-foot rangefinders from a Navy cruiser. With those, you could just about see around trees at half a mile.
I will use different words.
If it is a short distance between objects (in depth direction), the image is 2D. Like the two branches.
If it is a large distance between objects (in depth direction), the image is so 3D.
The final image between 20m and 50m is a combination of 3D distant bushes and 2D for branches of a single bush.
Agreed with "telescopes". Some people use "barrels",some people use "oculars"; this is the vocabulary in use. When in Rome ...
A few (other than you) use "telescopes", indeed.
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WJC
Well-known member
"Oculars" should never be used in this situation.
jafritten
Well-known member
Ted, I know exactly what you mean. The 2D effect is brought about by what one may refer to as "telecompression": the distance (in depth) between two objects seems smaller than it really is. The higher the magnification the stronger the effect. The effect is there in every binocular and can also be observed in telephoto lenses. The image seems compressed. The 3D effect is brought about by the offset of the objective lenses, as explained by WJC in post #2.
When the distance between two objects is small (the branches, say 30cm in depth) telecompression works against the 3D effect. The 3D effect is more dominant when objects are farther apart (the trees, say 30m in depth).
I observed the effect in a 10x roof prism binocular also. At shorter distance.
Telephoto lenses have this effect, even a 200mm (35mm camera) is clearly doing that. For this, I know the explanation.
jafritten
Well-known member
I use a 500mm telephoto for wildlife and bird photography (see my gallery, if you like). What I can say is, that the effect seems to increase with distance and focal length. So, I think it possible that a lower magnification porro has a better 3D effect because the counteracting telecompression will be less pronounced. Also, the distance between the viewer and the object will have an effect, I suppose.
WJC
Well-known member
Could you please explain to us how a single lens of a telephoto could have a 3-D effect at all? Since the 3-D effect is a property of imaging from two simultaneous vantage points and a telephoto lens has only one?
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elkcub
Silicon Valley, California
Not entirely, or even necessarily. The attached article might help.
I tend to favor the Gibsonian view myself, wherein 3D perception is determined by the brain reacting to gradients within the visual scene. Clearly, one eyed folks can walk, drive cars, and fly airplanes, — all of which require spatial distance perception. No stereopsis needed.
Ed
WJC
Well-known member
Hi, Ed (and others),Not entirely, or even necessarily. The attached article might help.
I tend to favor the Gibsonian view myself, wherein 3D perception is determined by the brain reacting to gradients within the visual scene. Clearly, one eyed folks can walk, drive cars, and fly airplanes, — all of which require spatial distance perception. No stereopsis needed.
Ed
I hope you realize that you are one of a handful of people on any group of bino forums who could cause me to doubt myself. Even so, while I know you are CORRECT, I believe the substance of the position is INCONSEQUENTIAL to everyday observing as:
— The vast majority will defer to my original assessment of the matter that the 3-D effect is the result of seeing an image from TWO vantage points (at relatively shallow distances), simultaneously as has been found accurate for more than 120 years.
— Some people can take advantage of this CONDITION, although I would argue it is not an EFFECT but that a majority would render the condition tenuous at best.
My oldest was born with severe strabismus. Because of this, I had numerous conversations with optometrists, ophthalmologists, neurosurgeons, and finally ophthalmic surgeons.
At the end of his first year of life (attached), I had to trust his vision to a poor untested surgeon named Zane Pollard of Atlanta’s Northside Hospital. We took a big risk with our son. That poor surgeon was so young, he only had 19 degrees and certificates adorning his office ... yes, I counted. Billy—now, Will—was corrected to 7 degrees, with prism in the glasses doing the rest. That fixed him up pretty good, at least until he gets tired. When he gets tired, all bets are off.
Thus, I am familiar with the condition, though not enough to be easily conversant. While pursuing further, Dr. Pollard recommended I talk to a local neurosurgeon, whose name I have long forgotten, who explained the concept to which you have referred. Please rest assured I will go over the document you have provided me; many thanks.
Sadly, consider what I have experienced during my 20 years of visiting bino forums, I must rely on my knowledge that so many things discussed on them either don’t exist in the real world or if they do, realities of the condition are mislabeled.
Please note the attached image. The customer owning this binocular said she didn’t see a problem!
“Everything looks fine to me.”
Sometimes you just have to stop arguing with people and let them be WRONG!
