Coc is always a factor. You can change the viewing distance or the print size, and the depth of field changes.
Bob > > 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 > [email protected] > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] 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 > > [email protected] > > 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 [email protected] > http://www.red4est.com/lrc > > > -- > PDML Pentax-Discuss Mail List > [email protected] > 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 > [email protected] > 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 [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
