Comment by fsckboy
7 hours ago
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
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-...
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"