One for the Knowledge base - Lens lengths.

OK. I’ve seen this mistake several places and figured I’d like to get the right answer down in writing.

I have seen several references to 35mm lenses as “wide angle” On a 35mm SLR camera this is true, but the Blender camera is modeled after a movie camera.

The length of the lens is determined so that when it matches the maximum dimention of your image, you get a normal image (the veiwfinder magnification is 1). 35mm is the height of SLR film, the width is 50mm. (Standard prints are 3.5" by 5.0", right?). But even though 35mm a movie camera uses the same film as an SLR camera, the film goes through sideways. 35mm is the width, the height is ~20mm. Therefore, 35mm is a “normal” lens, 50mm a short telephoto (portrait) lens, +80mm a long telephoto, 28mm a wide angle, and 15mm a ‘fisheye’. etc…

Of course we don’t have a veiw finder, (we look directly through the film) so the point may be moot.