Yes I was bothered by this. I mean, how does mere cropping or masking change
the DOF? Doesn't make sense to me.
Andrew Fildes
afildes@xxxxxxxxxxxxx
On 20/11/2010, at 7:26 AM, usher99@xxxxxxx wrote:
> BP writes:
>
> "Let's remember, before this gets too clouded. A 50 mm lens has the
> same dof
> as a 100mm lens, if the 50 is cropped to the same coverage area as the
> 100."
>
> Well almost but not quite. Even with the thin lens assumption the FL
> term for near and far limits of dof do not fall out. The distribution
> of the dof changes with a higher percentage of the dof distal to the
> plane of focus with shorter FL's. Not really much shift at the 50 and
> 100mm choices but pick something wider and there will be a larger
> difference. Dr. Focus concurred with this from a post a year or two
> ago.
>
> Would be thrilled to see a full wave dof calculator for even one
> complex lens--perhaps ping Zeiss.
>
> Skeptical about thin assumptions, Mike
>
>
>
> http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
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