[oasisbob]

It sounds like you know this already, but as any portrait photographer would note, changing the focal length is not equivalent to cropping. It's roughly equivalent, at best.

ie, Telephoto lenses bring a different perspective which includes distance compression. It's very apparent when photographing human faces.

[jaffa2]

If you take a shot with a 35mm and take same shot with a 85mm and then crop the 35mm to the same fov as the 85m the image will look _identical_ (not withstanding lens characteristics etc) the compression you talk about is due to the _distance_ between the subject and then lens changing . You will get the same compression effect if you shoot with a 50mm from 30 feet away …

[radiowave]

Changing the focal length doesn't inherently change the perspective, and (resolution and lens aberations aside) is exactly equivalent to cropping.

What changing the focal length does do is (e.g.) make you stand further back, and that changes the perspective, causing distance compression, etc.

[Daub]

True. A change in focal length is exactly equivalent to moving the vanishing points further away/closer to the picture plane. See the vid at the bottom of this page:

https://rmit.instructure.com/courses/87565/pages/perspective...

[oasisbob]

Ahh, you're right. Thanks.