P3D Re: Impact Of Internal Focusing on Lens Depth Of Field

[Eric Goldstein <egoldste@xxxxxx>]

RDJ92807 wrote:

> It appears that
> internal focusing has the effect of less depth of field.....


Hmmm. According to Kingslake what you are describing is impossible! DOF
is a function of FL, aperture and focusing distance and that's it. He
states that DOF can be increased in a lens by increasing one of the
distortion parameters (I forgot which one), but it does not sound like
this applies to your situation.

I do have an internal focusing Canon 200mm f/2.8, and have observed no
DOF differences with this lens compared with a conventional lens which
focuses by extention.

Maybe the next step for you is a more controlled shooting situation to
try to quantify the difference?


Eric G.


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