Archived posting to the Leica Users Group, 1997/08/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Curt Miller wrote: >If there are any doubters among us, just get out a 50 Leica lens and = an 80 >Hassy lens (or a 35 Leica and a 50 Hassy). See what the DOF scales = show for >f/8 (or F/whatever you choose). >Think this is sort of a common misperception about applied optical = theory. Gee, I was always told that at a 50 is a 50 is a 50. That the depth of = field for any 50mm lens, no matter the format, is always the same, just = more or less coverage. Hoping that I was right, I decided to check it out on a couple lenses. = Are you sitting down??? The Canon FD 35mm lens at f/16 shows about 4ft = to infinity. A Mamiya 35mm C at f/16 says about 2.3 ft to infinity. = Yes that's right, the Mamiya says it has more depth of field. I = couldn't believe it. So I compared another. The Canon FD 85mm at f/22 = says 15ft to infinity. The Mamiya 80 C at f/22 says 7 feet to = infinity. How can this be????????? My real world experience tells me this Mamiya 35C doesn't deliver sharp = images period. Someone at Mamiya had to be playing with those circle = of diffusion numbers to show that the Mamiya has more "depth of field". = Anyhow, if I'm shooting at f/16 I usually set the infinity mark to = around f/8 as a safety margin and sometimes bracket focus if it's = really critical. Theory is fine, but doesn't always play out in practice. Sorry, I = don't have equivalent Leica lenses to compare yet. Duane Birkey HCJB World Radio Quito Ecuador ***** Message Was Scanned For Viruses ***** =