---Pat Warnshuis <[EMAIL PROTECTED]> wrote:
>
> The constant selected for the circle of confusion
> varies from authority to authority. The FotoSharp
> slide rule uses .025mm.
Right. Some people use 0.03mm and others, including Zeiss, use
0.025mm. As a rule of thumb, the circle of confusion is 1/1750 the
diagonal of the film format.
> Yes. Now use Thom Hogan's c=F/1000
I question the validity of this formula since it results in a circle
of confusion of 0.1mm for a 100mm lens, which is 4 times greater than
the normally accepted standard. It also implies that the circle of
confusion for a 1000mm lens would be 1mm!
>
> Question, Berg: Do your calculations confirm that at
> f16 the near focus distance is approximately 1/2 the
> hyperfocal distance?
Patrick, I'd need to know the object distance in order to estimate the
near and far focus distances.
Berg
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