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
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