P3D Re: 1/30 rule doesn't work for macros!

[Tom Deering <tmd@xxxxxxxxxxx>]

On 8/12/98, Dr. George A. Themelis wrote:
>>The 1/30 rule-of-thumb does not work for macros.  It assumes that some
>>objects in the photo will be at infinity.

Shnipt
>(I know it works
>because many people are using it and are getting good results).

That last sentence is the kicker, George.  Who, exactly? (Thumping on table
and spilling beer.)

My own limited knowledge of the subject is based on the work of John
Bercovitz, who credits Bob Mannle, Steve Spicer, and David Jacobson.  His
writings on the subject are in the Photo-3D archives.  I quote:

>Many fairly simple approximate formulas of
>varying accuracy and usefulness have been
>offered over the years.  All of them do poorly
>in  closeup situations.  (snip)

>For instance, using twin
>SLRs (50 mm lenses) for a scene with a near point of 1.8 meters
>and a far point of 2.2 meters, b0 by this formula is 193 mm for an
>easy-to-view 1.0 mm deviation.  This setup has been photographed,
>and the scene is indeed easily viewed by anyone, though all other
>formulas predict that it is not viewable.

I could be wrong.  Who's using the 1/30 rule for macros?  What lens and
interaxial to you use?

Tom



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