Compression is Real

Started 7 months ago | Discussions thread
Donald B
Donald B Forum Pro • Posts: 10,422
Re: Longer lens *or* cropping

kiwi2 wrote:

Donald B wrote:

FingerPainter wrote:

Donald B wrote:

Mike CH wrote:

kiwi2 wrote:

You need the longer 400mm focal length for it to work.

Or you crop. The effect on the so-called “compression” is identical. You loose resolution, yes, but the ‘“compression” is identical.


Cant remember. Does the dof stay the same as well ?

If you crop, the DOF gets shallower. That's because to get the same size print from the cropped image you have to enlarge more, and thus blur circles that were just barely small enough to be indistinguishable from points on the print from the uncropped image have been enlarged so they are now distinguishable from points.



He's wrong though. He is talking about something different.

A 400mm f/4 lens will have a shallower DoF than a 100mm f/4 shot that has been cropped.

As can be seen here between a 27mm f/1.8 and a 125mm f/1.8 shot...

I know, i did my own test. The background blurr was way smoother


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