Re: [Leica] Incident Metering

[Michael Bell <MBell@mail.utexas.edu>]

>Harrison McClary recently wrote:
>
>"Too bad Fred Ward is no longer on the list as his dissertation on
>incident metering is the best worded description of why and how to
>use them I have yet seen."

and John McLeod commented:

>Too bad indeed.  If anybody knows where this description can be found, I'd
>love to see it.

I saved one of Fred Ward's postings on the subject.  Please find it below.

mike

- ---------------------------------------

Date: Sat, 10 Aug 1996 12:52:28 -0500
From: Fred Ward <fward@erols.com>
Organization: Gem Book Publishers
Mime-Version: 1.0
To: leica-users@mejac.palo-alto.ca.us
Subject: Re: MR4 meters
Sender: owner-leica-users@mejac.palo-alto.ca.us Precedence: bulk
Reply-To: leica-users@mejac.palo-alto.ca.us

This is my semi-annual message about a seemingly endless thread.

These are observations made as a photographer, not as a collector and not
as a comparison shopper. In a paragraph or so I hope to share four decades
of experience about a dozen or more light meters.

1. On the grander scale of expensive and carefully made objects, light
meters for photographers are relatively inexpensive items not made to great
tolerances and not meant to be perfect. Smallness has usually been a main
goal, and price of course. But great quality is not an issue with amateur
products. Therefore, do not expect too much.

Chris has observed what photographers have known for years, that same brand
or competing brand light meters seldom reproduce the same readings
reliably. Go into a camera store sometime and ask an idle salesperson to
show you a dozen meters and take a reading of the same object with all of
them.

And then there are the known difference among old CdS, Selenium, and all
the new battery-operated meters. Each has its own unique response to color.
They cannot all read the same.

And there is the basic concept to deal with. We generally believe that all
manufacturers use the 18% guideline and make their meters to deliver a
reading based on an 18% target. That is just not true. Any manufacturer can
use any formula it chooses. It can have one cell, 2, 4, 5, 6, or 10
metering cells and read all over the frame, giving weight to one part or
another (usually favoring the upper center for horizontals and screwing up
thing on verticals). As the speaker at a computer conference one began his
talk, <You want standards. You say there are no standards. Tell me what you
will buy and I will make it a new standard.>

Meters vary... when new, when old, when batteries are changed, when dropped
or vibrated in airplanes, or just because entropy is a reality.

2. That said, I find the main flaw in all this concern about accurate Leica
meter readings rests in a fundamental fact. All Leica meters read reflected
light... either from a window on top of your camera to a a behind-the-lens
cell, to spots on the shutter curtain. It does not matter how well adjusted
to 18% any meter is (and the 18% is no more and no less accurate than say
15% or 20% would be), if you are taking a reflected light meter reading of
your subject, you will get an acceptable reading only part of the
time.....the part that has a scene that just happens to be reflecting 18%
back toward the camera. Want to know how often that is? Most folks find it
is about 80% of the time for family shots.

That a reflected light meter works for anyone at all is a testimonial to
film latitude (and the diligent work by a few dedicated photographers who
really study a scene and try to find something that seems to be 18%
reflective, or use of a gray card). The 5 stops or so latitude in color
negative and b/w film saves the day for reflected light meters. Color
slides are seldom right-on with such readings. (And I can already hear the
incoming replies, <Oh, but mine are>.) They simply cannot be.

Look at the place with the most invested in a day s photography. With
movies costing tens of millions, every day is worth hundreds of thousands
of dollars. You have never and will never see a film photographer, whose
exposures have to be dead-on, use a reflected meter. He knows they do do
not work. Only incident light is read when the readings are important.

Do some tests with slide film. Do a long and medium portrait of anyone
against a white wall, then against a black wall, then in open shade, and
then in the deep woods. Look at the reflected light results. Do the same
with an incident light meter and look at the skin tones.

Do portraits of a Caucasian, an Asian, an Indian, and a Black with a
reflected light meter on slide film and see what you get. Of even cheaper,
carry around an incident light meter for a while and see what it reads
after your Leica meter gives you a reading. They both cannot be right, can
they?

I offer this conclusion. If you have and love the beautiful little Leica
meters, by all means use them. But if you want truly accurate exposure
readings for all films, use an incident light meter. But also remember,
incident meters also vary because of the things mentioned in the first
paragraph. Test a few to get one that seems to be reading accurately.

And now, to rest until winter........

Fred Ward