Well, lots of people talking about DOF with different format and they will
have the same DOF when shooting at same magnification. Is it really the
case? think about shooting a full size portrait with a 300mm at F5.6 and the
other with a 35mm at the same aperture. How will the background looks? Even
by calculation the DOF is the same, but the background clarity is completely
different.
C.H.Ling
>>From: "Terry and Tracey" <foxcroft@xxxxxxxxxxxxxxxxxxxxxx>
>>
>>In a John Shaw book, he says a 90mm lens has the same DOF whether it is
>>mounted on a 35mm, 6*6 or a 5 *4. I'm so confused.
>
>Yes, it has the same DOF *on the imaging medium.* Now blow that 4" x
>5", 6cm x 6cm, 35mm, and 4mm x 6mm CCD sensor image up to an 8" x
>10", and the DOF will be different in proportion to the print size.
>
>Say for illustration purposes that the circle of confusion from this
>lens is 2mm on the imaging medium. That is about 1/6th the area of
>the CCD sensor, but less than 0.40f the 35mm frame, and less than
>0.010f the 4x5 frame. So the end-print DOF is better the larger the
>imaging medium for a given focal length and aperture. (Please forgive
>minor inaccuracies in this "back of napkin" analysis... feel free to
>flame me for gross inaccuracies... :-)
>
>So if I screwed up here, please correct me, but it doesn't make sense
>that you could dramatically increase your end-print DOF simply by
>using smaller film. Otherwise, we'd all be using 110 film, and 8x10
>view-camera landscapes would simply not be possible! (Yea, I'm
>ignoring tilt for the sake of simplicity...)
>
>
>: Jan Steinman <mailto:jans@xxxxxxxxxxx>
>: 19280 Rydman Court, West Linn, OR 97068-1331 USA
>: +1.503.635.3229
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|