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Re: [OM] Digital depth of field - C2500

Subject: Re: [OM] Digital depth of field - C2500
From: "C.H.Ling" <chling@xxxxxxxxxxxxxx>
Date: Sun, 11 Jul 1999 09:02:44 +0800
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



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