Archived posting to the Leica Users Group, 2001/02/07
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]> A 100mm lens at > f/1.4 focused at 20 feet (exact same image size on the film as the 50mm > example), the DOF is from 19'7" to 20'5". The depth of field is EXACTLY the > same. EXACTLY 10 INCHES IN BOTH CASES for the given COC. > > From the exact point of focus, DOF extends 1/3 forward > (toward the camera) and 2/3 back (away from the camera). > Jim If the second point (1/3, 2/3 etc) is true then why does the d.o.f extend exactly 5" forwards and backwards (1/2, 1/2) in the example you gave? BTW the image size of a 50mm lens at 10 feet is NOT the same (by quite a bit) as 100mm lens at 20 feet for a 24mm by 36mm negative. And film size DOES matter when comparing the coverage angles of a lens.