By one measure, you could actually say the shot from the small-sensor camera actually has more "magnification", as you're magnifying a smaller image on the sensor to fill the same sized print. But, despite that, the small-sensor camera still ends up with more DOF.
On Sat, Sep 16, 2006 at 04:46:53PM -0400, graywolf wrote: > Just to clarify my other post on this, a 70mm on the digital has exactly > the same magnification as a 105mm on on 35mm film if the images are > framed the same and printed the same size (and they would necessarily > have to be taken from the same distance), and thus has no effect on the > DOF. In this particular case only the difference in aperture diameter is > giving the 70mm a bit more DOF. > > -- > graywolf > http://www.graywolfphoto.com > http://webpages.charter.net/graywolf > "Idiot Proof" <==> "Expert Proof" > ----------------------------------- > > > Mark Roberts wrote: > > John Francis wrote: > > > >> On Sat, Sep 16, 2006 at 01:28:26PM -0400, Mark Roberts wrote: > >>> Ryan Brooks wrote: > >>> > >>>> Adam Maas wrote: > >>>>> At f2.4, the 70 is about perfect for me. Essentially the same length > >>>>> and > >>>>> speed as the legendary Nikon 105 f2.5, which is a superb portrait lens. > >>>>> > >>>> You are getting more DOF with the 70mm though. > >>> Not true. Not at the same subject magnification, anyway. (And that's > >>> what you'll be doing if you compare both lenses as portrait lenses.) > >> Actually, Mark, Ryan is right. > >> > >> A portrait taken with a 105mm lens at f2.8 on a full-frame camera will > >> have a shallower depth of field than the same portrait (taken from the > >> same spot and enlarged to the same size) > > > > Right. But I specified "same subject magnification", not "taken from > > the same spot". And "same subject magnification" is pretty much how > > everyone does portraits: You frame as a head shot, waist-up, 3/4 or > > full length and compare two lenses with this view. I've never heard > > anyone saying. "Well this Lens 1 has shallower depth of field with a > > head shot than Lens 2 does with a 3/4 shot": It's not a meaningful or > > useful comparison. > > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
