dof HAS ZILCH to do with format, its all about magnification which is object size vs image size. object size vs image size ignores format. That said, if you are using the same lens focal length, and same distance of the object, and same f-stop, the DOF will be identical in the image regardless if its APS or 4x5 format. the format only changes the angle of view, not the DOF.
JC O'Connell [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Matthew Hunt Sent: Thursday, November 13, 2008 9:46 PM To: Pentax-Discuss Mail List Subject: Re: FA 1.4/50mm tested by DPReview On Thu, Nov 13, 2008 at 9:29 PM, JC OConnell <[EMAIL PROTECTED]> wrote: > In that case, FF and aps format would be the SAME DOF, neither one > would have "deeper" dof. And print size is not a factor either. You are incorrect. The DOF depends on the following factors: Lens focal length (f) Lens focal ratio (f-number, N) Subject distance (s) Allowable circle of confusion (c) (I'm following the notation of: http://en.wikipedia.org/wiki/Depth_of_field) In this discussion, we're talking about a given lens at a given f-number with a given subject distance. Thus everything except the allowable circle of confusion is the same. The allowable circle of confusion depends on the image format, because small formats require more enlargement to achieve a given print size. See, for example: http://en.wikipedia.org/wiki/Circle_of_confusion#Circle_of_confusion_dia meter_limit_in_photography With all factors the same, except CoC which depends on format, you can easily see that DOF depends on format. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
