Archived posting to the Leica Users Group, 2000/08/31

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Subject: [Leica] Clarification of DOF pre-exposure visualization.
From: Bryant <>
Date: Thu, 31 Aug 2000 15:14:40 +0000 ()

Hi Luggers,

> Yes, you can use tables, formulas, lens
> inscriptions, and numerous external methods, but you cannot substitute
> looking at it, at working aperture, and actually SEEING what is sharp and
> what is not.

    I guess that Mr Brick thinks that by throwing a black cloth over his head,
and looking through the viewfinder of his Leicaflex, he'll "see the boekh".
Well he will, but it will depend on the screen he's using.  If you were to
view the same scene at f/8, say, with my old Exakta with is non-fresnel 3 cm
thick GG screen, an original Leicaflex, and an R8, you'd see 3 slightly
different scenes.  The finished pictures would be almost identical, as long
as the sun was behind you (that old Tessar on the Exakta flares a bit),
and virtually all 50mm lenses are diffraction limited by f/8.

    So I'm back to my original point.  The only way you can *really* know is
to have the finished prints in hand, and remember the effect for next time.

    I've got to agree that the DOF scale on the lens is a good 1st order
approximation only.  DOF is different for different subjects.  The depth of
field for a group of flowers, with their inherently soft outlines is greater
than that for a field of pebbles, with their sharply delineated outlines.
Then, the DOF lever on the SLR is rather nice.  But not totally accurate!  

    We're splitting hairs down to atomic size.  Any non equipment nut would
view the three above mentioned pictures with his/her criticism directed at
weather the picture were interesting or not.  The very subtle differences in
sharpness would not be noticed. 

    Tom (The-Silly-Server's-Still-DOWN! :-()

Fanaticism consists of redoubling your efforts
when you have forgotten your aim.

                -- George Santayana