Edit0: Obviously you're also see the thing you're trying to get a picture of better

> effect a telephoto has

They're saying that it is not a property of the lens, but rather of the perspective of the scene viewed from a distance. You'd get the same effect using any focal length lens, taking the shot from the same location, and cropping appropriately.

Perhaps in contrast to depth of field which is a property of the lens.

I'm looking at the portraits of the woman on the beach and I'm not understanding how to get from one to the other with cropping. What am I missing?

They could have used the 35mm lens at the same distance as the 150mm lens and simply cropped and the perspective compression would be the same (it'd just be a lower resolution image).

Of course, on many cameras you then would get a smudgy or pixelated mess.

What you're describing as correct is what people understand. Of course it's the fact that you're far away. I think it goes without saying that you can't use a telephoto lens inside of a room or something.

And yes, of course you could take a wide picture and make a crop. But the resolution would be terrible. The whole point of a telephoto lens is to take that tiny crop of your environment at full resolution.

I'm sorry you learned it wrong at age 14 and maybe wherever you got it from really did explain it badly. But it's standard for professionals to talk about the effect of a long lens in this way, that the camera will be further away.

Of course analog zoom > crop, but only because reality < theory.

Anyway, I'd say you're technically correct but you might miss some angles and have some holes in the resulting images. But now with gaussian splats and AI we could reconstruct holes easily

Also, satellites photographing the Earth do it by moving the camera, and they can produce compression effects beyond what you'd get just because of their distance.