What does "correct perspective" mean?

Tom, you have a real blind spot that really is preventing you seeing past your own opinion. As I said, I can't put it any plainer. The problem with perception is yours, and not because I don't question my assumptions but:

I did not say that, Though there is a typo I think the meaning is still clear enough: viewing an image at a point in front of this will create cause us to see a distortion in that perspective that is often referred to as "telephoto compression"

The affect is apparent, not real. I also said:

Or to reveal: How far away do you have to move to see close up perspective?

And:

So tell me where the null point is on your scale? At what point mathematically does a photo with baked in geometry that is foreshortened in exact accordance with the maths of image formation reach a correct perspective. What is the nature of that correct perspective? Is it when we see the object correctly foreshortened, or exactly as depicted in the photo, or the point where it no longer appears foreshortened as in at the point where it becomes elongated? Remembering that the foreshortening is baked into the 2D image as a function of distance alone.

Please explain this mathematically. Because I can explain how it's possible perceptually, and it's entirely a function of distance both in the taking of the original image and the viewing of the print.

No, it doesn't, perspective is a function of distance alone.

Your inability to see this stems from your own inability to question your base assumptions and the massive blind spot they are creating in your thinking. I've been as clear as I can be without actually dictating to you because to understand this you really need to work it out yourself because only then will you break out of your tunnel vision instead of trying to fit everything I say within it.

I'm Offski. TTFN. 😀

Because I really do want to get away from this, and don't really want to leave a question in the air, I'll give my version of the simple answer. Tom, I'm simply asking posing questions so you can order your thoughts.

So here goes. There is a centre of perspective where apparent relationships between objects are preserved and we see a natural perspective, or one closest to that we would see if standing at the spot the camera took the photo.

If we take a photo of a distant barn (and I'm deliberately using an object in the landscape that has a linear perspective to preserve), it is foreshortened as geometry dictates.

If we view that barn in the photo at a point in front of the centre of perspective then the depth of that barn appears compressed, at the point it looks normal beyond that point it looks longer, up to a point because as we move further away to view the image the barn in the image reduces in scale and so looks as though it's further away to a point where we stop seeing the perspective altogether.

The barn in the photo always looks like a distant barn we simply make errors of assumption about it's depth when we view at a point other than the center of perspective. There is no point where at which you can view a distant object in a photo where it will take on the appearance of a wide angle view or wide angle distortion.

Similarly there is no point as you move closer to a wide angle shot of a near object where it will take on the perspective of a distant object. We simply make errors of assumption about it's depth. And there's also a limit about how close you can get to the photo.

So the following statement is incorrect:

The perceptual side comes when we define natural, foreshortened and elongated against viewing distance. Though it's tough to show this as human perception generally looks at an image, makes assumptions about perspective, preserves consistency of understanding and so in effect perspective in images appears quite static over a wide range of viewing distances.

The image is always an image of a foreshortened barn, it never changes. So when we view an image of a distant and therefore foreshortened barn and see it as normal rather than foreshortened it means that you do not see the absolute perspective in an image at the centre of perspective, you see a correct one.

This perceptual effect takes a little more explaining, of why you see the barn at the correct size rather than the absolute perspective of the foreshortened barn as contained in the image.

But everything below the quote can effectively be ignored if all you require is a working understanding.

You are very determined to blame my thinking. It is your thinking that is the problem.

When you say something I assume that you mean what you say.

This clearly says that viewing an image from closer that the centre of perspective causes us to see telephoto compression in the image. You can wriggle as much as you like, but that is what the statement means to most rational people. It is consistent with what is said in the Manual of Photography (in the pages following the extract given in the OP) about the flattening effect on perspective when using long focal lengths.

This statement is just a red herring. It has no meaning unless you define precisely what you mean by "apparent, not real" in this context. It is waffle intended to confuse the reader.

I get the very strong impression that you, yourself, have no clear idea of what you are talking about. As a distraction technique you claim that I have "tunnel vision" or a "massive blind spot". It is your own thinking that you should be worried about.

I have had enough of your time-wasting. Like most conspiracy theorists, you make a load of accusations against your critics - it is an effective distraction technique to try to draw attention away from your own shortcomings. I should have recognised it earlier by your incessant harping on what you claimed were my faults.

I will ignore further posts by you on this subject.

Tom, I'm done. See above.

I have started a poll (at the top of the page) for anyone who would like to participate - entirely optional, of course.

I just hope you don't take the results of the poll as scientifically conclusive to the original premise. 😳

Good heavens! There is absolutely no chance that I will do that. I hope nobody else does, either.

The scientific method is clear: it is not possible to find the truth by taking a vote on it.

The concept contained in the OP is absolutely fine, with all the definitions.

It was just tongue in cheek...

Cancelled! (I confused posts from two different threads!)

Thank you to all who voted in this poll. Any more?

The situation where the final viewed image subtends the same angle of the vision of the viewer as did the scene to the camera is what I call "natural" (not to be confused with "normal", a term I abhor, especially if someone claims it's "50mm" without qualification). I would not use the term "perspective" for this because that's a term reserved for the position of the camera relative to the objects in the scene, having nothing to do with the way the image is viewed, which is a separate and mostly unrelated topic (changing the way you view an image doesn't change the size relationship between objects in the image, only changing the camera position or the position of the objects does).

Projection can also be related. For example, a circular fisheye image is "natural" when projected onto the inside of a hemisphere, such as is done in dome theaters.