Originally posted by ChristianRock The main reason that I *want* FF is for distance perspective. Which I assume is the reason why landscape photogs use large format. I'll give an example… the other day I took a picture of my son in a big wooden train. I used my 35mm 2.4 which is my "normal" lens. It included everything I wanted in the picture, but the vagons behind the engine looked a bit smaller than the engine itself. If I took my eye off the viewfinder and looked to the scene, the train looked a certain way. Looking through the viewfinder, the background looked more distant and the wagons looked smaller. A proper "normal" lens is supposed to let you see the scene the same way the natural eye sees it. I'd need a "short telephoto" (50mm) range on APS-C for that, but then I wouldn't be able to include as much of the scene as I'd like.
I notice this in a lot of backgrounds when using my "plastic fantastic" as my walk around lens. It bothers me but not so much that I feel I *need* the change. It would just be a nice to have.
Will this "focal length changes perspective" myth never die? Perspective is not affected by focal length, or lenses, or cameras. Perspective is controlled by
distance and orientation to subject/background only.
Object A and B are the same size. Object A is at 10 feet, object B is at 20 feet. Object A looks twice as big as object B (20/10). Move back 10 feet and A at 20 feet now only looks 1.5x bigger than B at 30 feet (30/20). You don't notice this effect because you have a fixed AOV with your eyes, and you are used to seeing things far away as taking up a small part of your vision. When you use a longer focal length to magnify a small part of your FOV, it will look unnatural, hence the "compression" illusion. In reality everything about that part of your FOV is the same as before, just viewed bigger now. If there is ever a difference in relative sizes/positions of objects between shots of different focal lengths, it is because you
moved the camera (or distortion, which is a lens flaw, not a property of focal length).
Try it yourself. Take any two shots with any two rectilinear lenses of different focal lengths pointed at the same targets
from the same spot. Crop the shorter one to match the FOV of the longer shot. There is no difference in perspective, which you will see very clearly once you match the angle of view, no matter how you got to that AOV, by cropping, zooming or both.
See the second page of this thread where this is discussed extensively, and I provide proof with photos doing this exact experiment I describe:
https://www.pentaxforums.com/forums/169-pentax-full-frame/257907-just-simple-ff-2.html
Also, before anyone brings it up, the stretching you observe at edges of wide angle shots is not a matter of perspective, but a geometric property of rectilinear (
gnomonic) projection, trying to get a spherical field of view onto a flat plane (the sensor/film) while keeping straight things straight. It is tied to angle of view, not focal length, and will look the same on any shot of the same angle of view barring distortion. Crop these edges out and you will see that nothing about the center has changed.
Last edited by Cannikin; 04-19-2014 at 05:08 PM.