The question was regarding relative DOF, COC is not a factor. The only way to increase DOF from whatever your reference is, is to decrease IN CAMERA magnification or increase f-stop number. All that other stuff is moot. You cant change the relative DOF of an image after you shoot it.
JC O'Connell hifis...@gate.net -----Original Message----- From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf Of Larry Colen Sent: Monday, April 06, 2009 5:47 PM To: Pentax-Discuss Mail List Subject: Re: Trading resolution for depth of field On Mon, Apr 06, 2009 at 10:32:37PM +0100, Bob W wrote: > > So, if I'm willing to trade resolution for depth of field, am I > > better off using a wider angle lens and cropping (my intuition says > > yes), or do I get the same benefit by just combining pixels (which > > would also reduce noise) for a larger circle of confusion? > > > > To calculate the nearest (dn) and furthest (df) points in focus use > the following formulae: > > dn = U * F^2 / [F^2 + (U * c * f)] > df = U * F^2 / [F^2 - (U * c * f)] Ah. Thanks. Focal length is second order factor, circle of confusion is first order, so focal length has a greater effect on DOF, than CoC (pixel size). > > where > c = circle of confusion > U = subject distance > F = focal length > f = f-number > > To calculate the circle of confusion > > c = (v * D) / (1000 * S) > > where > v = film format / image size > D = viewing distance > S = print size > > Source: The Professional Guide to Photo Data, 3rd edition, by Richard > Platt. > > Very easy with a spreadsheet. > > Bob > > > -- > 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. -- The fastest way to get your question answered on the net is to post the wrong answer. Larry Colen l...@red4est.com http://www.red4est.com/lrc -- 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.
