Fisheye

[aam1234]

I asked that question in another thread, but didn't get an answer.

I've always wondered about the cut off point between a fisheye lens and a wide lens. Do people agree on a certain point (talking 35mm here).

Thanks

[mbze430]

okay I'll bite, what is cut off point?

[aam1234]

The point where a WA ends and a fisheye starts.

[kawter2]

The first is the rectilinear lens, This is the typical lens which renders all straight lines in the subject as straight lines in the image (see diagram below). It's pretty much the way our eyes see things and it's exactly the way a pinhole cameras sees things. For normal and telephoto use, a rectilinear lens is ideal, however for extreme wideangle use it isn't. Objects near the edges of the frame in very wideangle shots are "stretched". It's also impossible to make a rectilinear lens with 180 degree (hemispheric) coverage. In fact it's very difficult to make a rectilinear lens with more than about 100 degrees of horizontal coverage

The second type of lens is the fisheye lens. A fisheye lens renders straight lines which don't run through the center of the frame as curved (though lines running through the center remain straight). Objects at the edges of the frame are not stretched, but they are distorted. It's easy to make a lens with a diagonal coverage of 180 degrees ("full frame fisheye") or even with a horizontal, vertical and diagonal FOV of 180 degrees ("circular frame fisheye") - though this results in a circular image with the rest of the frame dark. Fisheye lenses were first made for scientific use, since with hemispherical coverage they can image the entire sky on a single frame and so were useful for astronomical and meteorological studies. The first "fisheye" camera was a pinhole camera that was filled with water, but luckily technology has come up with more convenient ways to make fisheye images!

http://www.bobatkins.com/photography/technical/fov/lenses1a.jpg



This might help

[KevC]

Hm. I always thought a fisheye would have a FOV of 180deg. Less than that I guess it'd be WA... ?