Archived posting to the Leica Users Group, 2008/05/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Jeff, In my first consideration of this issue, I did not think about the corners. When you think it through, it is ALL about the corners. I stand corrected. Jim Nichols Tullahoma, TN USA ----- Original Message ----- From: "Jeff Moore" <jbm@jbm.org> To: "Leica Users Group" <lug@leica-users.org> Sent: Saturday, May 10, 2008 11:22 AM Subject: Re: [Leica] Leica R-10 at Photokina 2008 > 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 > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >