[LargeFormat] Anyone Home???

[Richard Knoppow]

----- Original Message -----
From: "Stuart Phillips" <stuart.phillips@rcn.com>
To: <largeformat@f32.net>
Sent: Wednesday, December 04, 2002 7:59 PM
Subject: Re: [LargeFormat] Anyone Home???


> Richard, another amazing answer that goes in the "keeper"
file. Thanks for
> your erudition.
>
  Thank you.
  I think perhaps some of the differences seen in old
photographs come from the characteristic curves of the
films. In looking over the published curves from Kodak and
Ansco/Agfa I find that the "portrait" films had upswept
curves, the general purpose films had either straight short
or medium toe with fairly long straight lines. In practice
the difference is in the reproduction of mid gray tones vs:
highlights and shadows. Very long toe or upswept films
reproduce mid grays darker than straight line films where
the same shadow and highlight points are chosen for
printing.
  Most modern films are relatively short toe, relatively
long straight line types. The notable exceptions are Tri-X
and Plus-X sheet films. Plus-X has now been discontinued but
Tri-X is still being made. Kodak Ektapan also had an upswept
curve. I think this type of curve may be helpful in
producing certain effects in portraits where one wants to
exagerate skin texture for instance. I've also used Plus-X
to good effect on some seascapes where the characteristic
exagerates white caps and clouds.
  Until some years ago one could also obtain orthochromatic
films. The lack of red sensitivity changes skin tone
reproduction. I think the use of ortho film with upswept
characteristic was what Karsch used for his male character
portraits. One can see a definite difference in overall tone
reproduction in his portraits of women. I suspect there he
used panchromatic film, perhaps with straighter line D-logE
to brighten the mid tones, including sking tone.
  Of course there were also lighting differences and the use
of makeup on women, but the difference in tonal reproduction
can also be seen in backgrounds and clothing.
  I think the main differences in modern vs: old photographs
may be more technique than material, however, there is
certainly a smaller choice of material for B&W now than,
say, thirty or more years ago.
  I think it may be possible to get something of the effect
of ortho film by using a suitable cyan filter but probably
not exactly the same.
  The use of multi coated vs: uncoated lenses is often
attributed with the differences but I suspect that it
doesn't account for it, at least not entirely. Remember that
much old portrait work was done with lenses like Goerz
Dagors, which don't have much flare. Although lens flare can
approximate a long toe by reducing the contrast of the
shadows it has little if any effect on highlight contrast,
so I don't think this is the answer.
  As before, I would like some specific description of the
effect wanted since I am at this point just guessing.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com