[Leica] Re: Equivalent Focal Lengths

[leica@rakitzis.com]

>Yes, Doug, that's exactly what I'm saying. Forget the math. You can see
>it with your own eyes. Just set up your 2-1/4 camera with 75mm lens on a
>tripod and look through it. Note exactly what you can see on each side
>of the frame. Then hold a 35mm camera with 50mm lens exactly above it
>and see what you can see side to side in the viewfinder.

>I also have experienced that an equivalent lens on a square format
>camera somehow "feels" wider, but no matter how it "feels," it isn't
>actually wider. The side to side angle of view of your 75mm lens is 40
>degrees, and a 49mm lens on 35 covers that same 40 degrees.

This is an arbitrary distinction. If you measure to the vertical of the
35mm format, and say that you need to crop to a square, then suddenly
the 75mm square in 6x6 format becomes significantly wider.

If you crop your images to a quasi-panoramic 3:1 aspect ratio, then you
can tilt your medium format camera diagonally and actually fit a slightly-
wider-than-6cm panorama into your viewfinder, I figure it's about 6.4cm
on the long side.

This may sound absurd but I actually HAVE made compositions with a Rollei
tilted at 45deg.

I guess we can discuss this until we are blue in the face, but I think
it's worth "doing the math". Look at the image circles which lenses
for the 6x6 format need to have, and compare to the image circles cast
by 35mm lenses. In that context the only metric which makes sense to
compare is the format diagonal.

Byron.