Archived posting to the Leica Users Group, 1996/08/10

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To: leica-users@mejac.palo-alto.ca.us
Subject: Re: MR4 meters
From: Fred Ward <fward@erols.com>
Date: Sat, 10 Aug 1996 12:52:28 -0500
Organization: Gem Book Publishers
References: <199608021747.LAA12657@central.bldrdoc.gov>

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

Replies: Reply from Jack Hamilton <jackham@execpc.com> (Re: MR4 meters)
In reply to: Message from "C.M. Fortunko" <fortunko@boulder.nist.gov> (Re: MR4 meters)