Archived posting to the Leica Users Group, 2000/05/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 06:31 PM 5/16/00 -0700, Mark (ON A ROLL!) Rabiner wrote: >Yes and the one third back rule is often not the case and after all that you >have to know just how far you have to stop down and personally I do like >to know >especially if I'm doing a Hand held Carrying around a bunch of depth of >field charts does not seem doable either >than carrying around a pocket pal. >A simple depth of field scale on the outside of the barrel of a lens would be >how hard to do? Cost how much? We seem a pretty traditional non-automatic bunch (mixing our own DK-20 from elements that we've dug from the ground ourselves and all) why not figure out our own DOF in the field too?...simply memorise these four easy steps from the heyday of photography when lenses were measured in good ol' inches: (distances in feet) cc= Circle of Confusion (a part of light theory that you will only ever need if you rely on formulas like this) HD = Hyperfocal Distance (distance between the NP and the lens) FL = Focal Length (If you don't know what focal length is, sell your 35mm cameras and buy an APS camera.) f = Aperture (same definition as above) NP = Nearest point of image that is in focus FP = Farthest point of image that is in focus FD = Focus Distance. (this should be on your manual lens or in your Contax viewfinder) DOF= Depth of Field (the points between NP and FP) Step 1. find Circle of Confusion for lens: CC= 1000/FL (use FL expressed in mm, not inches or cm) Step 2. find Hyperfocal Distance: HD=(12xf)/(FLxFL)x(CC/1) Step 3. find the nearest DOF point: NP=(HD+FD)/(HDxFD) Step 4. find the farthest DOF point: FP=(HD-FD)/(HDxFD) Yes, it's that easy. Who needs those modern DOF scale gadgets! :-) Carpe Lumen, Michael E. Berube http://www.goodphotos.com