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Message: <blockquote data-quote="looksharp65" data-source="post: 1934134" data-attributes="member: 83771">This is correct, and this compression seemingly changes the proportions of the elements from which the picture is composed. For instance, photographing the Moon behind a NY skyline with a super telephoto lens makes it look absolutely gigantic (well, of course it is, but we are not used to seeing it that way)Also, the proportions of well-known objects will be distorted by the telephoto effect. A car that is placed diagonally will look very strange with the further/rear end enlarged and vice-versa. Try a spotter and see it.So, in this regard, when viewing at long distance, there is no "stand-out effect" because a tree line will appear more or less like a wall.But when viewing at middle or near distance, the shallow depth of field in a higher-power binocular will create the stand-out effect I am trying to explain.Everything closer or further than the object you focus will appear very blurred, so the sharp object "pops out", thereby creating a different sense of depth perception than the 3D-effect. A lesser-magnification binocular will provide a vastly improved depth of field. This is why I adore my Vortex 6,5x. I need very little refocusing.But a 6x porro will have an immensely more prominent 3D-effect at mid-distance than a roof has.I fear I might not have the right tools to explain this in a scientifically correct way, but I will give it a try.The two eyes send their information through the visual pathways of the human brain, where they will finally reach the visual cortex, and this is when we experience vision.When looking (without binoculars) at the closer environment, the two eyes converge in order to get a single, simple and sharp view of the object one wishes to observe.Now, when you focus an object, for example 1 yard away, the eyeballs' convergence makes it appear as a single object. But at the same time, every object further or nearer will appear double, and out of focus. Scarcely this is being paid attention to, nevertheless it is a fact. We are only very skilled in ignoring such useless information.In the retinae, millions of cones form "corresponding points". These corresponding points consist of cones that receive exactly the same visual input when looking at infinity, like stars.However, when the eyes converge in order to obtain simple, unified vision, as opposed to diplopia, these points will not receive identical information because of the partial displacement of the retinal image.(if you watch a pen's edge at the closest distance you can get it sharp and/or converge, and first close your left and then your right eye, you will find that the images presented are not identical.The visual pathways compute and combine the information obtained from the millions of cones and finally form a perceived image that is "plastic" or 3D-ish. This is called fusion. Stereoscopic vision can be measured in small increments and inspection workers can be extremely skilled in finding small aberrances.So if you look close at an orchid, its delicate parts stand out and you can tell.Basically, what is needed to obtain the 3D-effect are, besides stereoscopic vision:1) Image separation2) Convergence3) SharpnessIMAGE SEPARATIONShould the retinal images be exactly identical, the visual pathways and the visual cortex have no deviation to compute. This is what happens when using a bino-viewer, a device with two eyepieces mounted on a spotter or telescope. Watching through a bino-viewer may be very relaxing compared to a monocular instrument, but it can never provide 3D-vision.CONVERGENCEConvergence will not occur if you watch infinity, but it will increase the closer to the observer the object is located. When using binoculars, convergence of the eyeballs will correspond to the virtual or perceived distance through the binoculars.So if you watch a branch 10 yards away with a 10x binocular, it corresponds to watching it at 1 yard.But this is not all. The displacement of the optical axises of a porro binocular calls for an increased convergence, in order to avoid double-vision.Compared to a roof, the image of the object you watch, unless at infinity, will be located closer towards the physical center of the binoculars, that is, closer to the right edge of the left barrel's visual field, and closer to the left edge of the right barrel's visual field.Thus, the displacement of the image is greater in a (traditional) porro than in a roof prism bin, and consequently the 3D-effect is more prominent.SHARPNESSShould the cones receive a defocused image, a state of confusion will occur.While the corresponding points and the visual pathways are able of very exact depth perception, they are dependent to focused light. A blurred light will cause a "circle of confusion" on the retinae, and the corresponding points will not be able to send information that can be coupled to each other, hence the signal information can not be processed.Consequently, binoculars with a reasonably wide sweet spot and a great depth of field will provide more useful information in this regard.If you have a tack-sharp maximum sweet spot low-magnification porro binocular, it will provide a 3D-effect at the maximum possible. The Fuji porro that you praise appears to be a good choice in this respect.Not my mother tongue.</blockquote>

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