Joseph wrote: >Too confuse you further, Albano:
>It is my understanding that when you go to an APS-sized sensor, the >appropriate circle of confusion decreases, giving less depth of field. >For example, fCalc uses a CoC of .025 for 35 mm., but .0199 for APS. >This yields lower dof. I'm not shure about this - I never quite understood this CoC thing, because it seems somewhat subjective - but I guess an enlargement made from a APS sensor has to be enlarged more than that from af 35mm negative, which means bigger need for a small CoC. I guess the difference could have a connection with the crop factor (0.01999 x 1,5 = app 0.02985), which would make the two enlargemnets appear equally sharp/unsharp. Joseph furthermore wrote: >The bottom line is, I believe, that a 50 mm lens on the *ist D or DS >will give less depth of field than the same lens on a 35 mm. camera. Even though I agree with you conserning the CoC, in principle, I think this above is just pushing it too far. A 50mm lense will produce the same DOF on any camera body. A 50mm lens will produce better (deeper) DOF than a 85mm - on any camera. A 50mm used with a APS camera will give better (deeper) DOF than an 85mm used on the same camera. A 50m lens used on an APS camera will produce a significantly better DOF than that of an 85 mm used on a 35mm camera (so, if yoy like low DOF in a prtrait this may be an issue to cinsider). A 85mm lens used on a APS camera may produce a DOF similar to or better than that of a 50mm on 35mm camera, considered it's used, so that the AOV will be the same. Isn't that right, folks? Confused Albano?? Take a look at this: http://dfleming.ameranet.com/charts.html Jens Bladt mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt -----Oprindelig meddelelse----- Fra: Joseph Tainter [mailto:[EMAIL PROTECTED] Sendt: 2. januar 2005 21:50 Til: pdml Emne: RE: Sensor-Size-Conversion-Factor-Confused... HELP "Still, the DOF remains unchanged. DOF is a function of Aperture and Focal length an focusing distance - nothing else. However, since you normally use shorter focal lengths for a smaller (digital) format (to get the sam AOV), the DOF seemingly gets better (deeper) for the smaller (digital) format, provided the AOV is the same. "I too noticed, that a little while ago, there was a posting (Paul Stenquist??) saying something about the DOF on a digital camera being different from that of the same lens, used on a 35mm body...??? I believe what he meant was, that a 300mm on the *ist D will equal a 450mm in terms of magnification on a 35mm, but still have the DOF of a 300mm, which - I believe - is true." Too confuse you further, Albano: It is my understanding that when you go to an APS-sized sensor, the appropriate circle of confusion decreases, giving less depth of field. For example, fCalc uses a CoC of .025 for 35 mm., but .0199 for APS. This yields lower dof. The bottom line is, I believe, that a 50 mm lens on the *ist D or DS will give less depth of field than the same lens on a 35 mm. camera. Joe
