[Leica] Leica R-10 at Photokina 2008

[jbm at jbm.org (Jeff Moore)]

2008-05-08-13:48:57 Jim Nichols:
> I agree with Gene.  If a lens will cover 36mm in width, it will cover the 
> same dimension in height. Hence, it should cover at least 36x36mm.

Er, what part of the Pythagorean theorem is confusing here?  Don't just
count on words which sound nice together; draw the two formats packed
into circles, with the enclosing circles just kissing the corners of the
enclosed rectangle (which might be a square).  If an image circle is to
be guaranteed to cover a rectangular format, the circle's diameter must
be greater than or equal to the format's diagonal. The format's diagonal
is the square root of the squares of the sides.

  http://en.wikipedia.org/wiki/Pythagorean_theorem

For 24x36mm, that's 43.3mm (hence the Leica MTF graphs which go from
zero to 21.6mm, half that -- the radius from center to edge of the image
circle which covers 24x36).

For 36x36mm that's 50.9mm.

50.9 is bigger than 43.3.

Sure, some current R lenses (especially the longer ones) may have
coverage to spare, but more coverage *would* be required.

 -Jeff