[MF3D.FORUM:308] Re: 1/30 voodoo (Oy!)

["Bill Glickman" <bglick@xxxxxxxx>]

Tom, what is your web site address that I can read up on this subject
matter... I am very interested...


----- Original Message -----
From: Tom Deering <tmd@xxxxxxxxxxx>
To: Medium Format 3D Photography <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Sunday, March 26, 2000 4:52 AM
Subject: [MF3D.FORUM:307] Re: 1/30 voodoo (Oy!)


> >>The 1/30 "rule" is sophistry masquerading as fact. You may as well use
dice.
> >
> >I don't know.  The 1/30 rule seems to be an expression of a simple
geometrical
> >relationship.                ^^^^^
>
> You put you finger right on it.  Yes, it *seems* to be simple, but
> it's not.  Please see my web page for a thorough explanation.  I want
> to be helpful, but others on the list have heard me explain this
> dozens of times.
>
> >But at least 90% of
> >my pictures do contain distant objects so the rule is always my
> >starting point.
>
> No.  Considering that MF cameras usually have a 75mm or 80mm lens,
> the 1/30 rule will _never_ be accurate, distant objects or not.
>
> Tom
>
>
>
>
> On 3/25/00, Oleg Vorobyoff wrote:
> >Tom Deering wrote:
> >>
> >>The 1/30 "rule" is sophistry masquerading as fact. You may as well use
dice.
> >
> >I don't know.  The 1/30 rule seems to be an expression of a simple
geometrical
> >relationship.  If that is not factual, what is?  The rule tells me
precisely
> >where the stereo window will appear once a picture taken with 35mm lenses
and
> >containing faraway objects is properly mounted.  So with a stereo
> >pair taken at
> >70mm spacing the window will appear at 70mm x 30, or about 7 feet.  The
rule
> >applies to other lenses and formats proportionally.  So a 1/15 rule
> >would apply
> >with a 17mm lens on my Canon or a 35mm lens on my Pentax 6x7.
> >Likewise, a 1/60
> >rule would apply to a 70mm lens on the Canon or a 135mm lens on the
Pentax.
> >
> >The 1/30 rule need not apply if there are no faraway objects, since
> >the picture
> >may be mounted with a nearer object at apparent infinity.  But at least
90% of
> >my pictures do contain distant objects so the rule is always my
> >starting point.
> >If the scene can tolerate some window violation or, conversely, needs
some
> >breathing room behind the window, I use the rule to move the ultimate
window
> >back or forward accordingly.  No sophistry - just previsualizing the
final
> >mounted picture, like I presume any good stereographer would.
> >
> >If I've got it wrong, please set me straight.
> >
> >Oleg Vorobyoff
>
> ---
> tmd@xxxxxxxxxxx    http://www.deering.org
>
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