Sunny 16 versus meters

[P3D George Gioumousis <georggms@xxxxxxxxxx>]

From: P3D P3D Michael Kersenbrock  <michaelk@xxxxxxxxxxx>
> > A properly used light meter can give results unmatched by any exposure
> > table or rule, because these rules by definition are incident only and
> 
> This is probably true.  Under optimal conditions, "thinking-only" can 
> probably at best only match using a light meter.  Why?....
> 
From: P3D  P3D Gregory J. Wageman  <gjw@xxxxxxxxxx>
> 
> Bob Howard writes:
> 
> >As I said before in this forum..the Sunny 16 Rule is not just some rule
> >of thumb that came from somewhere. It was devised by Jack Tupper of the
> >Kodak Research Labs (who I served with on ASA committees) from the
> >equations of illumination on a film plane, and the constancy of earth
> >illumination from the sun. IT IS GOOD ENGOUGH to test light meters. 
> 
> So how invariant are sunlight conditions around the globe?  Is a sunny
> smoggy noontime in L.A. really photometrically equivalent to noon in, say
> the Swiss Alps (and I don't mean in snow)?  What about seasonal variations,
> like noon on the summer solstice, vs. noon on the winter solstice at a

Contrary to what is quoted above, an incident light meter is actually
often just right for slides, which is what I take with my Realist format
camera, and some of the time with my Nimslo. Consider my serious photography,
which often involves a California native shrub with nice flowers, at far, near,
and closeup distances. With my Minolta Maxxum 700si, which has very fancy
through-the-lens metering, the far pictures will usually look pretty washed 
out. The reason is that the camera averages the flowers, the leaves, the
branches, and the ground. The ground is usually in deep shadow from the
leaves and branches, but the camera loyally tries to average everything.
Ergo, the flowers are washed out.

For this sort of work, an incident light meter is really better. Furthermore,
the f/16 rule is not bad if you can see a sharp shadow edge and your shadow
is markedly shorter than you are. The reason is that in both the tropics and
the temperate zones the light does not vary by more than one stop for some 
hours either side of noon on a clear day. Furthermore, if it's hazy, so all
you can see is a very fuzzy shadow, one stop compensates.

Suppose, as an example from the animal kingdom, you (say male) are at an
isolated beach and are photographing a naked young lady with a Minolta
Maxxum. You should know that the reading will depend on whether the 
background is white sand, dark sand, blue sky, or water. Aha, you say,
"I will set my trusty Maxxum to spot metering mode". Then you should
know that the reflectance of her skin is probably 36%, rather than the
18% the meter expects, so you should close down one stop. Unless, of course,
she happens to be quite dark-skinned, in which case Ansels Adam's advice
is to meter off the palm of your hand, which has about 36% reflectance
even for quite dark-skinned people.

Anyway, my point is that the f/16 rule is often adequate, and that sometimes
better than even a pretty good meter.

If anyone is interested, I will copy the chart on my Rolleiflex TLR and
post it. It should work just as well with a Realist.
-- 
George Gioumousis           /---\        |       /---\ 
                             o o         |       o o  
georggms@xxxxxxxxxx           |          |         |   
(415) 494-6276              \===/        |       \===/ 


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