if that trick doesn't work, then either 1. your viewfinder is not showing what you will shoot which is what everybody expects because otherwise how can you frame your shot, 2. you are not using a 50mm lens or 3. you are not using a 35mm SLR

the point of a "single lens reflex" system is that you can see what the picture will look like by looking through the same (single) optics

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dghlsakjg 11 hours ago | parent [-]

No. As I stated, if the trick doesn’t work at 50mm it is because you are using a viewfinder with a different magnification.

A Pentax MX for example shows .97x magnification at 50mm. It will work great for your trick. Meanwhile a Canon AE-1 has .83x magnification at 50mm meaning one eye will be seeing an image where everything is 17% different in size. It will be like one eye is looking at a 55 inch TV and the other eye is looking at a 45 inch TV. Or more accurately, one eye is looking at the same TV but from 17% farther away.

If you throw a 58mm lens on that Canon, the trick will work again because you are zooming in to compensate for the zooming out that is happening in the viewfinder.

Of course, none of this has anything to do with 50mm lenses being “standard”.

Don’t believe me? Go slap a 50mm lens on an SLR with very low magnification. Or read one of the dozens of articles and threads out there explaining your misconception. Here’s a great one: https://www.lomography.com/magazine/319909-cameras-in-depth-...

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fsckboy 10 hours ago | parent [-]

technically speaking, if your viewfinder has a different magnification, that is (to coin a word) Multiple Lens Reflex; you have added a lens. SLRs were invented to show you "what the camera sees" so you can tweak it perfectly on different dimensions.

you are describing a different system that does not show you what the camera sees. I'm not saying what you are talking about doesn't exist, I'm saying that your over-inclusivity takes away the value of describing what I described and is telling people "there's really nothing you can say, a million different things could be going on"

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dghlsakjg an hour ago | parent [-]

Every slr with an eye level viewfinder (instead of focusing on a waist level ground glass) has optics in it. It is an MLR by your wording. Your eye has to focus on the reflection of a ground glass within an inch or so, or else is viewed through a lens that makes it possible to see what the camera sees. You wouldn’t be able to focus with your eyes if there wasn’t another lens.

In other words, your “standard” lens is an artifact of the optics chosen to allow your eye to see the image.

In terms of what your eye sees: The FOV of what you are focusing on with your eyes is narrower than a 50mm lens. The FOV where your eyes can recognize symbols (can read letters) is wider than a 50mm lens. The FOV that your eyes can see from periphery to periphery is drastically wider than 50mm.

Quite simply put, the fact that on some cameras you can shoot with both eyes open at 50mm is an artifact of design, not some natural law. This is proven by the fact that there are cameras where you can do this with a 35mm lens or a 60mm lens. Camera manufacturers settled on calling 50mm at 1.0x magnification a standard view is arbitrary.

There is precisely nothing behind the common belief that 50mm is the same view as your eyes. It isn’t.

You can keep insisting otherwise, but it is in contradiction with physics and nominal human anatomy.

	▲	fsckboy 16 minutes ago \| parent [-]
		well, why don't you bring your physics and human anatomy arguing-from-first-principles over to wikipedia and let's see how long your changes last on that camera page :) good luck! https://en.wikipedia.org/wiki/Single-lens_reflex_camera opening paragraph "In photography, a single-lens reflex camera (SLR) is a type of camera that uses a mirror and prism system to allow photographers to view through the lens and see exactly what will be captured... SLR technology played a crucial role in the evolution of modern photography...the rise of mirrorless cameras in the 2010s has led to a decline in SLR use and production. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image.*