Re: Paired shots from different focal lengths

[P3D john bercovitz <bercov@xxxxxxxxxxx>]

> On the surface this is true BUT we also jiggled the images 
> to the same image size and DEPTH OF FIELD IS EQUAL AT THE SAME 
> F/STOP AT THE SAME MAGNIFICATION REGARDLESS OF FOCAL LENGTH.
 
Almost: f/number is relative aperture but the DOF is the same at 
the same _linear_ aperture (hole-in-the-iris size).  So if we took 
a picture with a 100 mm lens at f/8 and then took a picture from 
the same point with a 50 mm lens at f/4 but blew it up 2X, the DOF 
would be exactly the same.  It's an easy experiment to try and 
most folks have these two lenses for their SLRs so give it a go.
 
John B
 
O what a tangled web we weave,
When first we practise to deceive!
Sir Walter Scott


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