> Anyone even vaguely interested in photography knows about lens compression.
And here I thought lens compression doesn't exist:
https://fstoppers.com/originals/lens-compression-doesnt-exis...
And here I thought lens compression doesn't exist:
https://fstoppers.com/originals/lens-compression-doesnt-exis...
In my experience, which is limited to phone cameras and the like, they seem to produce realistic images at short ranges, but a landscape picture looks much smaller and more distant than how the scene seems to me as I take it, unless I zoom in. That has me wondering if there is some geometry that would give realistic-looking pictures at all distances? Perhaps if the camera is sized such that the lens-to-sensor distance is about the same as the eye-to-picture distance when viewing the images?
Another issue that I am wondering about comes from the fact that telescopes (and, I am assuming, telescopic lenses for photography) have an objective lens to produce an image that is much closer, and then an eyepiece (or whatever the equivalent is called in photography) to view that image. Does this have different perspective and foreshortening effects than a simple lens which merely casts an image directly on the sensor plane? To put it another way, for a given telescopic lens, is there, at least conceptually, an equivalent simple lens which would produce an identical image of any scene?
> That has me wondering if there is some geometry that would give realistic-looking pictures at all distances?
I don’t think so. Compared with wider angle lenses as in phones, camera telephoto lenses produce the compression effect when the nearer and further objects are relatively close to each other compared with their common distance to the camera. If you had three people at 5, 100 and 105 metres away the 5m one would probably be out of focus and look significantly larger than the two at 100 and 105m. A zoom lens allows the degree of compression to be changed, but the image changes as you zoom.
> Another issue that I am wondering about comes from the fact that telescopes (and, I am assuming, telescopic lenses for photography) have an objective lens to produce an image that is much closer, and then an eyepiece (or whatever the equivalent is called in photography) to view that image.
Cameras don’t have an eyepiece lens in the same way that telescopes and microscopes do. In DSLRs, there is a mirror that routes the light to the camera viewfinder. When a picture is taken, the mirror moves out of the way and the light from the lens directly hits the sensor. In mirrorless digital cameras, the viewfinder image is created electronically rather than optically from the sensor.
Most serious camera 'lenses' in fact have multiple elements. By way of example, a Nikon 20-200 lens has the following: 21 elements in 18 groups (including 6 ED lens elements, 2 aspherical elements, 1 fluorite element, 1 SR lens element, elements with Nano Crystal and ARNEO coats, and a fluorine-coated front lens element) [0]
[0] https://store.nikon.co.uk/nikkor-lenses-nikkor-z-lenses/nikk...
If you have access to camera with a manual hardware zoom, put it up to your right eye, keep your left eye open. Adjust the zoom on the camera until what you see with your right and lines up with what you see with your left.
That’s the perspective that you see at. Do this with a few friends and you’ll find out that you all see at slightly different “zoom levels,” meaning there can’t be an out of the box universal “eyesight lens.”
The perspective distortion comes for landscape photos are due to the field of view. So the absolute distance between lens and sensor doesn't matter, what matters is the ratio between that distance and the width of the sensor. As long as that ratio is the same as the ratio of the eye-to-picture distance and width of the picture, the perspectives will match.
The problem is that if you are looking at a landscape with your bare eyes, you will look at a quite large field of view. To reproduce that field of view when looking at the picture, you probably need to print it several meters wide, and look at it from a meter away or so. If you take a photo with the same field of view but print it at a handheld size, it will look "too small" and the perspective will seem exaggerated.
That's another issue, not caused by different lens or physics but by how our brains interprets what it sees. Our brains pick up and zoom on details subconsciously (and "compress" the uninteresting background) so you remember the details "bigger" than they are in reality.
That's why medieval cities on paintings have often towers twice the height compared to a photo of the same view. Same thing happens when you look at the Moon and then make a photo of it (without zooming). You have to zoom 2 or 3 times before it looks as big as "in reality".
The concept of "lens compression" is understood to include composing the subject to the same apparent size with the different lenses. Yes, of course standing in one place and compositing multiple telephoto shots will create the same image as a single wide angle shot. That's not how people shoot. You're not going to compose a 3/4ths portrait shot with a telephoto, swap lenses, and just stand there. You're going to walk in on the subject and recompose to a 3/4ths portrait.
If you switch to a lens with higher magnification, that's an indirect reason. It may or may not make you move farther away. But the distortion/appearance is due to the distance.
Also, you may crop photos (ie digital zoom) or use a different sensor size or sensor distance.
At the end of the day, the necessary and sufficient condition for the change in appearance is the distance.the lens is neither sufficient nor necessary.
The last 30 seconds of this clip https://youtu.be/yRBNA27N0ts
In this scene (if I remember correctly) the man on the right is coolly allowing the man on the left to believe that he's being threatened with being sent (by the approaching airplane) to another country where he would suffer a terrible fate.
The scene is meant to make it look like the airplane pilot has deliberately executed an impressive landing right next to the men, but apparently in real life it was quite far away (like a runway's length or so).
Another example is "we use AC power on the grid because it's more efficient than DC for transmission." Nope. High voltage is more efficient for transmission; we use AC only because Thomas Edison didn't have silicon carbide power transistors.