The Ansel Adams Fallacy: "True perspective depends only on the camera-to-subject distance"

I still can't help thinking that we're still missing the fundamental and simple point here.

The image of the real world projected on the retina, like the one projected on a 2D sensor obeys the maths of pure geometry,

Is not the same as/does not equal

The image you see "with your eyes".

There is a layer of processing, lets call it "The Twilight Zone" because of the symmetrical meaning it conjurers, and call the one rule of TTZ "light does not travel in straight lines through TTZ.

Because that layer of processing includes things like Constancy Scaling it does in a very real sense mean that light doesn't travel in straight lines through TTZ.

So if you were to ray-trace from "what you see" through the centre of perspective to the real world it would fail to line up with the image projected on the back of the retina, and so would contradict the maths of geometry.

Telephoto compression only happens when we look at photos of distant objects, we never see it in other photos.

Foreshortening, or compression is the mathematical and geometrical fact of how distant objects are rendered on the retina/camera sensor.

Again you ray-trace directly from/to what you see, an imaginary space. And again the maths doesn't tell you anything of the sort. The maths only tells you what the retinal image should be, it fails to describe the "what you see" because of TTZ, so using geometry to describe "what you see" means that by very definition it must contradict the retinal image and therefore must also contradict geometry. And because you keep using "what you see" as the true baseline and relate that directly to geometry you are off base mathematically.

I think this is so wrong, telephoto compression and wide angle distortion are the function of camera to subject distance alone, the proof, and challenge, is simple:

If the above statement is correct then you will only see "telephoto compression" in photos of more distant objects viewed from the wrong distance.

And you will only see "wide angle distortion" in photos of close objects viewed from the wrong distance.

These two are not reversible with viewing distance.

If you are correct then you can show me a solid example where this is reversed with viewing distance.

My explanation is here:

dprevived.com/t/the-ansel-adams-fallacy-true-perspective-depends-only-on-the-camera-to-subject-distance/5326/post/72306/

Light behaves according to the laws of physics, which are well understood. The laws of physics and mathematics apply right up till the light hits the retina. After that it is reasonable to call it "the twilight zone". However, the twilight zone does not apply before the light enters the eyes.

That is simply not true. The image projected onto your retina follows the normal laws of geometry. It is after that that the brain takes over and we are into what you have dubbed "the twilight zone".

No, telephoto compression can happen with any photo, if viewed from closer than the CoP. However, we only see telephoto compression in images that contain familiar objects whose size can be used to help us judge distance. Of course, we can be deceived in many ways. For example, the Ames Room: we assume that it is a normal room with rectangular sides and a level floor, whereas in fact the sides are not rectangular and the floor isn't level, so our depth perception reaches incorrect conclusions when it assumes that the sides are rectangular and the floor is level as in a normal room.

Foreshortening is not the same thing as compression. Foreshortening is the change in aspect ratio caused by viewing a flat object at an angle. A photograph taken from the same position will show the same foreshortening as seen by the eye (provided the camera and the eye are at the same viewing position).

Telephoto compression occurs when a photograph is viewed with a greater angle of view (from one side of the photo to the other side) than that of the camera when the photo was taken.

This is incorrect. As I said before, light obeys the usual laws of physics until it hits the retina of the eye.

The rest of your comments that follow from these, are also incorrect.

It is not that easy to find a single photograph that will show both. A wide-angle photo is needed to easily show wide-angle perspective distortion, but it will not have sufficient resolution to enable it to be enlarged sufficiently to easily show telephoto compression.

To my mind, the easiest way to demonstrate that wide-angle perspective distortion and telephoto compression are the converse of each other is to use a telescope (or monocular). Look through the telescope in the usual way and you will often see telephoto compression (everything looks much closer). Look through the telescope backwards and you will often see wide-angle perspective distortion (everything looks much further away).

Again I think you miss the point.

Here you link what you see directly to maths and the maths directly to light rays. Again:

You can only directly link the retinal image with the geometry of image formation. And as "what you see" by definition is a different image than the retinal one any maths that links directly to it therefore cannot also follow the same maths of geometry, because it cannot by definition describe an image different to the retinal image and still be correct at the same time. So your statement above must also be incorrect.

It's quite simple, but you keep treating "what you see" as the retinal image and keep relating it directly to image geometry.

Why not? It is easy to find images that display telephoto compression and equally easy to find images that display wide angle distortion. So why can't you find one that doesn't fit my exact definition? I've nailed my colours to the mast and allowed you anything that falls outside it. It doesn't have to be both. By your theory a UWA shot viewed from normal distance should also show expansion of distant objects because they are viewed at a distance behind the centre of perspective. Just sayin'.

Doesn't work. They look further away but the distance between the distant objects is not expanded or stretched, and the definition I'm using is a simple one: Wide angle distortion is where the distance between objects or even the appearance of the depth of an object is stretched, telephoto compression is where it appears compressed.

Andrew, you are shooting at paper tigers. It is a commonly used distraction technique by those who have nothing constructive to add to the discussion: attack your opponents for statements they haven't actually made. I have never said that our brains interpret the signals from our eyes in terms of geometry.

Please read carefully what I wrote, think about it and try to understand it. I am getting really tired of you repeatedly criticising me for something I have never said and do not believe.

If you look backwards through an 8x telescope, everything looks approximately 8 times further away. An object 1m away appears to be 8m away, an object 2m away appears to be 16m away. The distance between the two objects is 1m, but it appears to be 8m when looking backwards through the telescope. It's just the same as zooming out to an UWA shot compared to zooming back with your feet - they are not the same thing.

And it does. If you take an UWA shot of mountains that are a mile away, then they will appear to be much further away when the photo is viewed normally. I rarely use UWA lenses, so I do not have any examples to hand, but an online search will find plenty (e.g. here). Of course, unless you are familiar with that particular scene, you will not know if the mountains look further away than they actually are!

I think this is a reasonable example that shows both compression and wa distortion. I have to move back quite a way to see wa distortion but there is a point beyond which it is apparent to me.

Taken from this post earlier in the thread
dprevived.com/t/the-ansel-adams-fallacy-true-perspective-depends-only-on-the-camera-to-subject-distance/5326/post/70457/

The good thing to do (for me at least) is to stand back where I see wa distortion. Then move forwards through the cop to where telephoto compression is apparent, observing the change along the way.

Still the penny doesn't drop. So what does this mean then?

I have repeatedly pointed out (google it yourself) that it is mathematical fact that we do not see pure geometry when we stand at the same position as the camera as the extra layer of processing distorts it. And yet you are specifically stating that "what you see" is proved by the maths. In theory there is a point where the retinal image should be the same, and the maths can absolutely demonstrate what you see is different, and as the nature of a 2D image is inherently different to the 3D scene there is no maths that says the two should look the same either. I think you doth assume too much...

But I give up, I throw in the towel on this one.

And if we look at a wide angle shot then we find that though true with the foreground the effect diminishes with distance as is predicted by geomerty, distant items are rendered foreshortened and as the distortion caused by human vision becomes less effective with distance we can say that what we see should be at least roughly equivalent to what geometry predicts, see below:

The foreground appears to extend but the background doesn't relative distances appear stable. I've tried it through bins but the image is too small, but I expect it is the same as geometry predics the wide angle shot to be, i.e. mathematically foreshortening is a function of distance and I do not see this reversed, I do not see the distances between the background objects extending.

So telephoto compression is the effect where the distance between two objects appears compressed and wide angle distortion is when they look smaller? So your proof is that if I take a photo and move away from it wide angle distortion predicts that it will look smaller and this is dependant entirely on viewing distance.

Can't argue with that, so throwing in the towel here as well.

I'm not seeing any wide angle distortion, as in the shapes are stretched in this image at any distance.

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Most people would struggle to figure out the lens that took these pictures without EXIF data or other prior knowledge.

Yes, quite often the amount of foreground and the appearance of the foreground are sufficient clues to the ultra-wide angle of view.

There are two aspects of wide-angle perspective distortion, which I should have clearly distinguished. First there is the extension of distances away from the camera (the inverse of telephoto compression, which is the compression of distances away from the camera). Second, there is the distortion of shapes when they are projected at an extreme angle onto a flat image (e.g. a sphere appears not as a circle but as an oval shape). The second is often much easier to detect than the first, but it does not occur in the centre of the image.

You keep conflating different subjects. First it's perspective versus viewing condition, now it's perspective versus projection. Circles appear as ovals on the edge of a rectilinear image because of that type of projection. Such is not the case with all projections.

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Nothing strange there! It is not hard to imagine what a small crop would look like if you enlarged it. We are used to seeing pictures at all different sizes from thumbnails to huge. That's why people (like you) claim they see no difference in depth perception with viewing distance. Our natural depth perception only comes into play if we think we are looking at a real scene rather than a 2D image. Clearly, many people find it hard to do that, or simply don't want to do it.

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You need to read more carefully and try to understand what is being said, rather than just trying to find fault!

This discussion has become far too repetitive. I haven't heard anything from my critics that has caused me to doubt the conventional and long established science of perspective, merely crackpot theories that are unscientific and illogical.

So I will bow out of this discussion until someone comes up with something genuinely new and interesting.

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In a post in DPR, I made the following challenge:

The result was a deafening silence. No-one came up with any mathematical analysis to explain perspective distortion (either wide-angle distortion or telephoto compression).

Can anyone here answer those questions?

I agree Bob, I think that is probably true (at least in many cases). However, they should still be able to come up with a mathematically precise analysis of a given situation using their own definitions, wouldn't you think?