Re: Sunny-16 Rule

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

>The "Sunny-16" rule that people have been quoting seems wrong to 
>me.  I just returned from Hawaii (poor me) where I shot 15 rolls 
>with my "flat" SLR and my twin SLR rig.  On sunny, cloudless 
>days I was shooting Sensia 100 (slides) at f/16 at 1/30 to 1/60 
>second. In other words, I needed roughly one to two stops more 
>light that the Sunny-16 rule.... What's the scoop?

I don't know what the scoop is... My personal experience is that the
sunny-day rule WORKS exactly as stated in all the photography books I have
read (f16, 1/ASA).  Possible explanations for discrepancies:

 1. Side lighting (front lighting is required for SDR).
 2. Haze in the air (absence of distinct shadows, required by SDR).
 3. Too early or too late in the day.
 4. ASA of the meter was left at 64 or 50.
 5. Light meter is off.
 6. Aperture in camera was set at f11 or f8, not f16.
 7. Cameras set in "A" not "M" (can happen in my X-700)
 8. Camera shutter speeds/aperture markings are off.
 9. You like overexposed slides.
10. Partial eclipse of the sun was taking place.

There are three variables involved:

A. Lighting conditions
B. Meter reading
C. Camera settings

Assuming that B and C are correct, then explanations 1-4 and 10 will result
in conditions where the lighting was not a "sunny day" equivalent.

Assuming that A is correct (was indeed "sunny day") then it is possible
that the meter is off or set to the wrong ASA (4, 5) so you indeed
overexposed the pictures a bit but you did not see the effect either
because you like overexposed slides (9) or because the cameras were not
doing what you thought they were (6, 7, 8)

You seem to have a good knowledge of photography so I really don't know
what the scoop is.  But I do know that the sunny day rule as stated above
(f16 @ 1/ASA) is correct.

Regards -- George Themelis

PS. (not related to previous posting) Just saw first Realist roll of a
stereo newbie.  Most pictures overexposed by 1-3 fstops, some totally
washed out.  Only two pictures exposed properly in entire roll.  I was told
that exposure was decided using a spotmeter (this 3d newbie has some
photographic experience... previous newbies didn't own lightmeters and
relied on sunny day rule, producing properly exposed slides from the first
roll).  My conclusion for newbies (unrelated to posting I am replying to): 
If you don't know how to use a lightmeter (or spotmeter), better stick with
the sunny day rule!


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