If you are enlarging the image to achieve the same final print size, won't the
DoF be reduced on the APS sensor as the circle of confusion will be enlarged
further too? Will this negate the increased DoF caused by the shorter focal
length for the same AoV?
Nick
-----Original Message-----
From: "Jens Bladt"<[EMAIL PROTECTED]>
Sent: 02/01/05 20:24:13
To: "[email protected]"<[email protected]>
Subject: RE: Sensor-Size-Conversion-Factor-Confused... HELP
Hmmm....
Long story (the optical/scientific side) - I won't go into that.
Still, the DOF remains unchanged. DOF is a function of Aperture and Focal
length an focusing distance - nothing else. However, since you normally use
shorter focal lengths for a smaller (digital) format (to get the sam AOV),
the DOF seemingly gets better (deeper) for the smaller (digital) format,
provided the AOV is the same.
I too noticed, that a little while ago, there was a posting (Paul
Stenquist??) saying something about the DOF on a digital camera being
different from that of the same lens, used on a 35mm body...??? I believe
what he meant was, that a 300mm on the *ist D will equal a 450mm in terms of
magnification on a 35mm, but still have the DOF of a 300mm, which - I
believe - is true.
So, I believe what you are saying about the 50mm and the 85mm may very well
be correct. But of cource, by cropping the image (by using a smaller format)
you may in some cases also cut away some of the "out of focus" areas, which
may appear as better DOF.
Jens Bladt
mailto:[EMAIL PROTECTED]
http://hjem.get2net.dk/bladt
-----Oprindelig meddelelse-----
Fra: Albano Garcia [mailto:[EMAIL PROTECTED]
Sendt: 2. januar 2005 20:56
Til: PDML
Emne: Sensor-Size-Conversion-Factor-Confused... HELP
Hi gang,
I understand the APS sized sensors on DSLRs converts
your 28mm on a 42mm cropping image area, but if I
understand well, the depth of field remains the one of
a 28mm and also the distortion of image proper of the
original focal lenght remains, since the lens is still
phisycally the same, but cropped, right?
So, people who uses 50mm lenses as short teles for
portraits, still gets the dof and face features
rendition of a 50mmm but cropped, not the flatting
effect of a 85mm...
I'm right?
Regards
=====
Albano Garcia
Photography & Graphic Design
http://www.albanogarcia.com.ar
http://www.flaneur.com.ar
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