Another good rule of thumb to remember is that a 50mm lens on a 35mm sensor ("full-frame") is roughly the equivalent FOV of the human eye, i.e., what you see naturally.
I never understood that argument. By pure FOV the human eye is much wider. Of course it is not that simple, spacial resolution drops off to sides (while temporal resolution increases). This makes statements like "50 mm on 35 mm is FOV of human eye" not very meaningful.
if you take a 35mm SLR with a 50mm lens and rotate it vertically (portrait) and hold the viewfinder up to one of your eyes, and leave the other eye open, your binocular vision will merge the two images with no problem/distortion, as if you were not holding a set of lenses up to one eye.
since what you see through the viewvinder is what the taken picture will look like, it is neutral like/wrt your eyes, at the zero middle between wide angle and telephoto. (it's worth considering "who says eyes are neutral?" it's the system we are used to and our brain develops to understand)
it's non obvious to a casual observer that the mm units chosen for the image size (the image gets focused on a 35mm rectangle (you need to know the aspect ratio)) and mm for the focal length are measuring different things, but that's why you just need to "know" that 35mm and 50mm "equal neutral". there are more things measured in mm as well, like the actual width of the primary lens which indicates how much light is gathered to be focused onto the same square.
i'm not a photographer. i don't quite know the mm lingo for what happens when the image sensor/film is wider then 35mm, the large/full formats. the focal lengths "work" the same, but a larger image would need to be focused and that seems like it would require some larger distances within the lens system.
The way I understand is that it is not FOV but zoom level. If you look through a camera with 50mm lens, the subject and background should appear same size as when viewed with naked eyes. Doesn’t matter if it is full frame or crop sensor.
weinzierl|5 months ago
fsckboy|5 months ago
since what you see through the viewvinder is what the taken picture will look like, it is neutral like/wrt your eyes, at the zero middle between wide angle and telephoto. (it's worth considering "who says eyes are neutral?" it's the system we are used to and our brain develops to understand)
it's non obvious to a casual observer that the mm units chosen for the image size (the image gets focused on a 35mm rectangle (you need to know the aspect ratio)) and mm for the focal length are measuring different things, but that's why you just need to "know" that 35mm and 50mm "equal neutral". there are more things measured in mm as well, like the actual width of the primary lens which indicates how much light is gathered to be focused onto the same square.
i'm not a photographer. i don't quite know the mm lingo for what happens when the image sensor/film is wider then 35mm, the large/full formats. the focal lengths "work" the same, but a larger image would need to be focused and that seems like it would require some larger distances within the lens system.
fvgvkujdfbllo|5 months ago
Aurornis|5 months ago
This page doesn’t have any images but covers the concept quite well: https://en.m.wikipedia.org/wiki/Normal_lens
The concept of matching a picture to normal human vision goes back to the age of paintings, before any photography even existed.