Archived posting to the Leica Users Group, 1999/12/01
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 7:06 PM -0800 12/1/99, Jacques Bilinski wrote: >> The 100 APO macro may not be the best example because, if my recollection >> serves, the focal length shortens as you focus closer > >Yes, you are right about this, but I think that both the stated focal length >and the stated angle of view are for the lens focused at infinity. > >On that same brochure the angle of view for the 35mm lens is given as 64 >degrees and that of the 15mm (less than half of the 35mm) lens is given at >110 degrees (not 128 plus degrees). > >One way to convince yourself that angle of view is not exactly directly >proportional to focal length is by drawing little scale diagrams. You will >see that this rule is way off for very wide angle lenses, but a good approx. >for tele lenses. I think this is pretty well known by anyone who has used a variety of lenses or who understands basic trigonometry. Where is this leading us? * Henning J. Wulff /|\ Wulff Photography & Design /###\ mailto:henningw@archiphoto.com |[ ]| http://www.archiphoto.com