Does this exist?

[paul.deitch]

Is there some kind of non-electronic viewer where you look through and it overlays the different lens angles/focal lengths?
If so what's it called?!
Could be useful for teaching.

[Phunk]

The nearest thing I can think of is a 'Directors Viewfinder'

[paul.deitch]

Thanks for the feedback. The optical ones are pretty expensive for what I had in mind but...
I found this https://www.provideocoalition.com/magic-viewfinder...
Cheers

[Fordo]

There's quite a few directors view finder apps - put in your sensor size, and using the phones camera will give overlays for the angle of view for different focal lengths. Can only go so wide though as you're limited by how wide the phones camera lens is.

[G600]

Some rangefinders have markings in the viewfinder for different focal lengths.