Re: physiology vs. sensitometry

TERRY KING (101522.2625@CompuServe.COM)
11 Jun 96 05:27:20 EDT

Steve

This is how this thread began.

You say:

" What you say is completely true, but we do not "see" real life that
way. The brain integrates a "image" from the eyes shifting and focusing on
the scene. In this way the image formed has a huge dynamic range of
brightness. When making a print to try to express a full range of tones, we
are trying to recreate that mental image."

I know what you say is theoretically correct and I had always believed it myself
but it is a misconception.

One day last year I was out taking photographs with Richard Ingle who is both a
very fine photographer and a consumate printer. We stopped at Stoke by Neyland
parish church which is the one whose tower appears above the trees in many of
Constable's Dedham Vale pictures. The church is about eight hundred years old.
The interior is white-washed. In the west end of the church which forms the
support for the tower is a very high and graceful arch which looks, in
engineering terms, as if it is at the very limits of what is feasible without
the tower falling down. Through the arch and under the tower it was dark and
cluttered with ladders and chairs. The walls on either side of the opening and
the side walls of the church were white. Sun was shining through the windows and
lightening the lightly toned stone font at the base of my field of view on the
ground glass screen. I noticed that, despite all that I had thought was true in
relation to the contrast range that we can perceive, in reality it was not
possible with the bright light in front of me to see into the arch. I thought
that this was strange. I wondered if there was something wrong with my eyesight
so I asked Richard if he perceived the scene in the way that I did. He did. The
only way one could see the detail under the arch was to walk under the arch and
allow the eyes to adjust to the dimmer light there.

So when printing that scene to express the full range of perceived tones from
the point at which the camera was placed, the detail under the tower should NOT
have been included. The film was recording beyond the range of perception at
that time. Richard made a print inluding the detail undere the tower. That print
"

1. was not a record of what we saw

2. introduced clutter that we could not see at the time which detracted from the
purity of the composition

and 3. Removed the shadow under the tower, which we was what we perceived at the
time, and thus the mystery of the scene.

Yes we know that we can perceive a very wide range of tones but the reality is
that this is not the case under all lighting conditions.
Would you expect to see into the shadows beyond the range of a street lamp
especially if the light were between you and the shadows ?

I seem to be defending a truism here against attack from all sides.

Terry King

Both of you are completely correct!

mjc5@psu.edu