I think the "Sunny 16" rule is a bit misnamed.
The Sun shines with the same intensity over any place of the planet given a certain inclination over the horizon.
The rule is supposed to apply two hours after sunrise, two hours before sunset, (other say: with the sun more than 20° above the horizon) with clear sky, and - importantly - with the sun on your back, i.e. in front of the subject (with side sun you will want to open exposure a bit).
The rule is based on the fact that once the sun is high enough, the exposure will be basically the same throughout the day.
- Pollution can probably alter sunlight, but really not much unless you live in XIX century London, or XXI century Peking (Beijing);
- What complicates things is the reflectivity of the environment surrounding your subject.
I find that for a normal urban environment, with cobblestones and asphalt, EV14.5 ("sunny 13") is the right rule.
The sunny 16 rule was enunciated by somebody working in the US Navy, for "field" condition, with the sea reflecting sunlight on the boat, and light grey painted boats reflecting sunlight on the boat itself (paint makes a smooth surface which behaves a bit like a mirror).
I suppose the half a stop excess closing is due to these particular conditions.
In a "concrete jungle" environment the rule should be enunciated as sunny 13 IMO. But everybody goes on saying sunny 16 (possibly because there normally is no "13" on the aperture ring).
I usally use my meter. But I found that it is sunny 11 - 13.
I live in Oklahoma and even in winter on a sunny day (such as yesterday) my meter reading will be a sunny 16.
I've just shot two rolls of 100ASA b/w film, one in a Kodak Retina 1a and the other in a FED I. Using 'Sunny somewhere between f8 and f11' and extrapolating backwards accordingly, I was pleased (and surprised!) to find that I didn't have a single unprintable exposure amongst the 40-odd shots. It has to be said that some of the content was inevitably rubbish, but it was all reasonably well exposed rubbish. Part of this undoubtedly comes down to the Sunny rule, but as light levels fall guesstimation becomes more difficult and I believe that past experience plays a greater part. Using mainly a totally manual TTL metering camera and taking note of the indicated readings over the years in various lighting conditions undoubtedly helps when one is meter-less.
Here’s a particular version of the “Sunny 16” rule that has given recommendations that closely mirror what my incident light meters read around 42° 28’ North (Ann Arbor, Michigan) in the main part of the day. It's better than the simple rule because it takes a variety of lighting conditions into considerration.
Printed on the Inside of a Box of Kodak Plus-X pan, ASA 125 expiration 05/1998:
“Set your camera or meter to ASA 125 and shutter speed to 1/125 second.
Bright or hazy sun on light sand or snow f/16
Bright or hazy sun (distinct shadows) f/11—use f/5.6 for backlit close-up subjects
Weak, hazy sun (soft shadows) f/8
Cloudy bright (no shadows) f/5.6
Heavy overcast/open shade f/4—subject shaded from the sun but lighted by a large area of clear sky”
The weak link in the process is our ability to accurately access the lighting conditions. Early morning or late afternoon light is weaker than the main part of the day or in foul weather.
Of course, nothing beats an accurate light meter when exposures have to be correct.
I am unclear as to what the bold sentence means. Are you saying that in Texas at the same time of year and same light conditions of bright sun then if you were getting the correct exposure with say f11 in Texas you had to use f16 in England. I think I must have this wrong but clarification from you would be appreciated.
Originally Posted by thuggins
Thanks for the great responses. There were some good points that got me thinking, and looking back at the slides. First, it wasn't often sunny in England. The few times there was clear, unobstructed sun were in the late morning or mid afternoon. So it was high enough to be strong, but low enough to be right behind me and shining directly on the subject. The subject is the other part. Most of the shots were of buildings, with vertical sides reflecting the light straight back. The light-colored stone and brick reflected a lot of light, too.
This was very different from shooting landscapes. Foliage is much darker and horizontal surfaces don't reflect as much light toward the lens. I should heve remembered that a shear rock face will typically meter at least a stop brighter than the forest below it.
Any chance of clearing up my confusion about your sentence in bold?
I've been shooting film for more than fifty years and was raised on sunny 16 and know well how to use it, but IMO the human eyes are very poor instruments for evaluating fast changing lighting conditions because they react too quickly in a way that is imperceptible to the owner, and in this day and age when light meters are the norm and their cost can soon be offset by avoiding spoiled exposures but some photographers still insist on using sunny 16 out of some sort inverse snobbery to demonstrate how clever they are because they don't need a meter.
But isn't that the whole point of the rule? You don't trust your eyes, you evaluate the seen and apply an exposure based on the conditions and make allowances for cloud, shadow, time of day - because you can't trust your automatically compensating eyes.
Originally Posted by benjiboy
I use sunny 16 a lot - but don't think of myself as a snob. It is mainly because I am an enthusiast for old mechanical cameras, especially folding 6 X 6 cameras. Most of these have no meter. I find guessing the exposure is part of the fun. If I wanted to ensure I took a decently exposed picture I would use a meter - but chances are if it was an 'important' picture I wouldn't be using a folding 6 X 6 in the first place, I'd use a camera with built in metering.