From: "Lawrence Smith" > On 2/11/03 4:56 PM, "Brian Blankenship" <brian@bngraphics.com> wrote: > > > I don't know about the D1x, but the D30/D60 use a .5" chip, that's like > > shooting with 110 film (but better resolving power of course), which > > results in more DOF. > The D1x has a 1.5 multiplier. While the DOF is increased somewhat it is no > where near what you described. I shoot at f2.8 - f5.6 all the time using a > variety of lenses and the DOF is easy to control quite what you would > expect. Have you used the D60 much? re DOF lets look at circles of confusion, and accept the usual definition that it relates to the percieved depth of field seen in an 8x10 print. the coc values are generally accepted as: diameter film format 0.250mm 8x10 0.125 5x4 0.60 6x6 0.029 35mm now lets see what the DOF for some of these are and how the DOF relates H=hyperfocal distance f= focal length c= diameter of coc u= object distance N= f number of lens a couple of formulae: Hyperfocal distance= f^2 / (NxC) near limit of sharp focus= HxU / (H+U)-f far limit of sharp focus = HxU / (H-U) -f run a few calculations through this and you will find that a larger format will have a greater DOF than a smaller format using the _same_ focal length lens. therefore If I were to use a 50mm lens on a half frame digital camera the DOF would be substantially less than for a 35mm camera (it's effectively a telephoto lens on this format) BUT if I were to use 'equivalent' focal length lenses (lenses on each format that has close to the same field of view) the smaller format will produce a greater depth of field. a 50mm lens on a 35mm camera has a greater DOF than an 80mm on a 6x6 For a 1/2 frame ccd the FOV equivalent is produced by a 21mm lens karl
