Most of the time it doesn’t escalate into a contentious debate, sure. Lots of discussions where the things I read change my view on things, and I’m sure my own comments change others’ view on things too.

But by the time it starts to take on the style of an actual debate, there’s less room to convince someone who feels strongly enough to engage in the debate. Still, it’s worth doing sometimes because in these public forums, the debate might be read by thousands of lurkers, some of whom didn’t feel strongly enough to have a view, but walk away convinced that one of the two sides is more correct.

I know I’ve been convinced of a side while watching two others debate.

Yeah, yeah, the stubborn handles that just won’t go away, I’ve heard it before.

Yes, but I bring it up for the specific example of using our own eyes to achieve this effect, rather than relying on a camera. We don’t have a choice to change the focal length of our own eyes, or even crop the image, but the effect is still there.

Technically focal length doesn’t matter directly, only indirectly, because the phenomenon is almost entirely defined by the distance from the camera and the subject. If you have a 50mm lens and take the photo as far away as the 200mm lens, the person will look roughly the same when cropped down to the same apparent size (minus the loss of resolution from cropping and a smaller effective sensor size).

If you slap on a 200mm lens on a camera within 2 meters of your subject, though, you might not be able to focus, and if you can you wouldn’t be able to fit their entire face in frame.

But that also means our eyes, with our fixed focal lengths, can experience the same thing, by just moving closer or further away from a subject. Our visual cortex automatically adjusts a lot of things, but get up close and see someone’s ears or hair shrink in relative terms compared to their nose, or get far away and see their nose get back to a normal ratio to their eyes or ears.

Side note, this is a big reason why I don’t care for selfies. I don’t like the distortion.