struggling with a FF vision in my µ4/3 world (img)

Started May 25, 2012 | Discussions thread
Chinaexpat
Junior MemberPosts: 38
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Re: would not have helped -- a common misperception
In reply to Eamon Hickey, May 30, 2012

actually DOF does change because the magnification of the background object changes.

For example if the tree in your 1st diagram is a bit over 40' high and it is reduced to a bit less than 1" on the image plane that is a 1:500 magnification.

In the 2nd diagram only about half the tree is included so the magnification raises to 1:250

FOV, Focal length, sensor size, subject distance... these are all just variable proxies for magnification

Don't forget that there is no such thing as a "zone" of sharpness only a plane (only truly flat in a theoretically perfect lens). At high magnification sharpness falls of sharply away from the plane. At low magnification the falloff is rather gradual. So called DOF is just an arbitrary standard of what constitutes acceptable sharpness. And it is affected by focal length!

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