steve harley wrote:
On 2015-03-07 12:03 , John Francis wrote:
The basic problem is you have three defining factors to consider. They
are:
1) The size of the subject you are tring to capture
2) The size of the final image you are trying to create
3) How far away from the subject you can place the sensor
doesn't the resolution of the film or sensor figure in?
in other words, assume system A can resolve details to 0.01 mm on its
film or sensor, and system B can only resolve 0.02 mm details … won't
the effective depth of field be larger on system B, simply because with
its lower resolution you can see less difference between perfectly
focused and slightly out-of-focus details?
Yes, exactly, if you look at the formula for the calculations, both
sensor resolution and print size, your eyeball's resolution, come into play.
This is the DoF calculator I tend to use:
http://www.dofmaster.com/dofjs.html
and here are the equations that they use:
http://www.dofmaster.com/equations.html
If you look at the DoF scale on your camera you'll see that distances on
your camera are in a logarithmic scale and the distances for near and
far are just adding and subtracting logs of the ratios for the near and
far distance. In short, anyone who has used the DoF scale on a manual
focus lens has used a very simple slide rule to multiply and divide.
--
Larry Colen [email protected] (postbox on min4est)
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