Archived posting to the Leica Users Group, 1998/04/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi David, I'm no optical wizard but I do consider myself a math wizard. The depth of field of a 180 mm lens with a 2x converter is the same as a 360 prime. Another interesting point about d.o.f. with the 2x converter is that you use the d.o.f. scale for approximately 4 stops larger. In other words if you set the 180 with 2x converter at f/16 (f/8 per the lens setting) your d.o.f. scale for f/4 would be accurate. I'm not familiar with R lenses but I'll bet it doesn't have f/4 on the d.o.f. scale. So, if your 180 with 2x at f/16 (f/8 per the lens setting) your total d.o.f. would be about 12 inches. Art P.S. I'll bet sping is turning Annapolis into one big photo op about now. >Optical wizards all...a question: > >Will the depth of field available with a (mythical) Leica 360/4 lens set >at 5.6 be exactly equal to the depth of field available using a Leica >180/2.8 and the 2x converter at max aperture? Or (answering my own >question) would the depth of field for the 180/2x combination result in >depth of field exactly equal to a 360/2.8 with a 2-stop neutral density >filter? > >I have the 2x Apo converter, but am thinking, for DOF reasons alone, >that I need long primes. Ouch. > >Curious in Annapolis, I remain, > >David W. Almy >