Archived posting to the Leica Users Group, 2000/05/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]"M.E.Berube - GoodPhotos" wrote: > > 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 FUNNY!!!!!!! LOL Mark Rabiner call me Spock!