P3D Re: To Focus or not to Focus?

[jacob@xxxxxxxxxxxxxx (Gabriel Jacob)]

Bill Stickley writes:
>I was trying to find a way to use Hyper focal without memorizing or
>taking one more sheet with me. 

Here is an easy way to determine the hyperfocal setting and the
range in focus without any tables (for Realist or similiar f.l. cameras).

HYPERFOCAL SETTING 
Set distance dial = 160/aperture

DETERMINING CAMERA IN FOCUS RANGE
Half of hyperfocal setting = x feet to infinity
or 80/aperture = x feet to infinity

This is for a circle of confusion (I just love this term!) of 0.001 inches.

Example: For f11, set distance dial to 160/11 = 14 feet (rounded off)
         Half of 14 gives us, 7 feet to infinity will be in focus.  

>Even more interesting is that the two cameras do NOT agree. Are
>there some differences in DOF scales or is it because of the
>differences in the 2.8 and 3.5 lenses? 

There very well could be differences in the DOF scales but I don't
think it is because of the different lenses (2.8 vs. 3.5). I say
this because I have a 3.5 Ilex and 3.5 D.W. They both have different
DOF scales. The Ilex uses a CoC of 1/1000 (0.001") of an inch and
the D.W. uses a CoC of 1/750 (.00133") of an inch. Why this is so,
I am not sure. Marketing?

Gabriel


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