DOF is never determined by print size, its all about in-camera magnification and f-stop used. I think mentioning print sizes or cropping just confuses the issue. jco
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of John Francis Sent: Tuesday, October 02, 2007 11:25 PM To: Pentax-Discuss Mail List Subject: Re: putting old lenses on digital cameras On Tue, Oct 02, 2007 at 08:08:37PM -0400, Adam Maas wrote: > > The conversion is 1.6 times for the small Canon bodies, so take your > 28, > multiply by 1.6 and you have the equivalent in 35mm terms (Which is 45mm > or so). And it's all because the sensor is smaller than a 35mm frame of > film, not because of the space the adaptor takes up. > > The conversion applies to all lenses and doesn't change. And it > doesn't > affect DoF, it's really just like a crop out of the centre of the 35mm > frame. Well, sort of. Maybe. *If* you keep your final print/viewing size the same as a cropped portion of the full print from that 35mm frame, then the DOF doesn't change. But if you enlarge then central cropped portion to the size of the full image you're changing the magnification, and so you'll also see a change in DOF. Roughly speaking you need to open up about one stop wider in the DSLR to get the depth of field that matches a comparable shot from a 35mm camera, when looking at full-frame images (using different focal length lenses). -- 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.
