Lance Bledsoe schrieb:
>
> This required a bit of thinking from me as well...
>
> In my mind, I look at it as if I have a regular 35mm frame
> which has been cropped. Everything about the lens, DOF,
> focus, etc. is the same, except with a smaller AOV.
>
> Lance
Yes, this is exactly what it is. With respect to DOF there are a
few things to consider, though. As you say, or at least as I
understand what you mean ;-), the circles of confusion on the
sensor are the same size as they would have been on film. This is
obvious, because the image on the sensor is just the cropped
middle part of the image on film. Now, if you enlarge both images
by the same factor in printing stage, you get two prints with the
same DOF, the one made of the digital image being smaller and missing
the outer parts of the bigger print. If you crop the 35mm image to the
same size, both images are identical, except for possible differences
in resolution caused by the different "sensors".
So far all is easy. It's getting a little more complicated if you try
to get images with the same AOV from both sensors and prints of the
same size. Obviously, the digital will need a shorter focal length for
that and the image will have to be enlarged more for the same print size.
The effect of this on DOF is, that the print coming from digital will
appear to have larger DOF, assuming both images have been taken with
the same aperture setting.
Thomas Bantel
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