Proving Sunny 16

When we first start out in photography, we learned certain rules which

as beginners we never question. Over time, these rules become

ingrained in our consciousness. They seemed self evident. There

isn�t a reason to give them any additional thought, but there should

be. I feel much can be learned by reevaluating these basic rules of

photography from a more experienced perspective. I�ve asked such a

question in another thread. What makes middle gray, middle gray? It

could have also been presented as why is a gray card 18%? The first

answer that comes to mind usually is "because it is."

 

It�s like the perennial children�s question, �Why is the sky blue?�

One possible and popular response is, �because it is.� Another

possible response explains that shorter wavelengths of light, such as

blue, are easily scattered by particles in the atmosphere creating the

illusion of a blue sky.

 

What about reevaluating the timeless Sunny 16 Rule? Is it just a rule

of thumb? Why use f/16 instead of another f/stop? Why use 1/ISO for

the shutter speed? What is the relationship between the Sunny 16 Rule

and the meter or the camera exposure? Is there any PROOF to support

Sunny 16?

I've never heard the "Sunny 16" rule. To quote a photo professor of mine, to make the correct exposure you "expose for the proper amount." I usually look at my scene and think about what I want to do with it. Do I want to use selective focusing to isolate a part of it? If so than I won't use f16, I'll use the proper apature. Do I want to freeze motion, or make it blur, is there motion at all to consider?

 

The only reasons I can think of for using f16 is that most lenses are sharpest 2 or 3 stops open from their maximum f-stop. As far as the shutter speed thing, I have no idea. I usually avoid the 1/250 and 1/500 on the lens of my 4x5 because I know those two speeds are about a half stop too fast.

The "sunny 16" rule doesn't imply that you have to use f:16, but that if you're not too far north or too far south, that for most of the year (how much depends on your latitute), on a clear day in full sun the exposure will be f:16 at 1/ISO speed of the film. You could use f:22 and double the exposure time or use f:11 and cut the exposure time in half, etc., just like with any kind of exposure.

 

Why does it work? Well, under the conditions specified, the light from the sun is relatively constant over most of the earth. Take an incident reading outside on a clear sunny day, and you should get f:16 at 1/ISO.

 

You might, however, also want to compensate for the reflectivity of the subject, so if you're photographing the proverbial black cat sleeping on a coal pile on a sunny day, you might choose f:11 at 1/ISO or equivalent to improve shadow detail, and if you're photographing a marble statue on a sunny day, you might choose f:22 at 1/ISO so as not to loose the highlight detail.

Sunny 16 used to come printed on every box of film. I think it still is. It doesn't require you to use F/16. All it does is give F/16 1/EI for an easy to remember rule. Simple proof for Sunny 16 is to go outside and test it. You can test it on a sunny day. F/16 at 1/EI. On a hazy day F/11 at 1/EI. On a cloudy day with shadows F/8 at 1/EI. On an overcast day with no shadows F/5.6 1/EI.

 

You know what they say. Nothings stops you from testing it. F/16 @ 1/EI is EV 15 right?

Interesting. Film boxes have exposure guides. In 1962; Kodachrome II was ASA 25; and the guide recommended 1/125 @F8 for our family's Kodak Retina IIIc. This is equal to about 1/30 @f16; like 1/ASA at F16..There is about 4 decades of film boxes and instructions somewhere in the world.

You can modify the rule for your loacation:) :<BR><BR><IMG SRC=http://www.ezshots.com/members/tripods/images/tripods-260.gif><BR><BR><BR>In the 1950's; there was a "safett factor" of 2X; in the ASA definition used prior to 1960. Here is a 1950's Rolleicord IV's exposure guide:<BR><BR><IMG SRC=http://www.ezshots.com/members/tripods/images/tripods-264.jpg><BR><BR><BR>A 1930's camera had H&D film speed ratings. Here is the exposure guide on a camera; for H.D. 4400 speed film; roughly a ASA 100 speed; maybe!. <IMG SRC=http://www.ezshots.com/members/tripods/images/tripods-261.jpg>

I'm reading the "because it is" answer and not the why answer? Is this proof that Sunny 16 is just a rule of thumb, or is this support for my argument that we occasionally need to challenge our complacency on fundamental concepts? I make it a personal policy to reevaluate many of the universally accepted rules of photography and have found it illuminating. The Sunny 16 Rule is just one of them. How deep does the rabbit hole go?

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David, I'm not saying that you have to use f/16 in the exposure, but why is it the Sunny 16 rule and not Sunny 11? Why not Sunny 11 at 2/ISO or 1/ISO?

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<i>under the conditions specified, the light from the sun is relatively constant over most of the earth.</i>

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That explains why you can have a rule.

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<i>Take an incident reading outside on a clear sunny day, and you should get f:16 at 1/ISO.</i>

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Yes, but WHY does this work? I believe that settling for such a superficial answer can impede a deeper understanding of the process. Let's make this a substantive discussion.

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The "proof" to support sunny-16 is essentially that a middle-gray object in direct sunlight emits about LV 15, or 320 candles per square foot. LV 15 makes it such that at f/16 the exposure speed is about the same as the ISO film speed. If the sun was twice as bright the rule would be called sunny-22. Under other well-known lighting conditions you could make up your own rules, like "my-local-ice-rink-1.4" or "full-moon-0.044" or "my-backyard-at-3pm-in-a-summer-afternoon-11".

 

(Why 18% middle-gray? because slide film has 5 stops of latitude, and 18% is exactly 2 1/2 stops from 100%, so that if 18% is exposed exactly in the middle of the curve, there's enough latitude toward the highlight to not burn out white details).

 

(Why is the sky blue? If you ever have the chance to see liquid oxygen, you'll know)

If one goes to Venus; it might be Sunny 22; maybe ?.<BR><BR>On Mars; it is about Sunny 11 or Sunny 8 ??<BR><BR>On Jupiter; it is about Sunny 4 before entering their atmosphere.<BR><BR><b>Once the ASA is defined; the rule's "fstop" varies with the light source.</b><BR><BR> Somewhere beyond Saturn; the sunny 1 rule works well; break out those Noctilux's :)

Stephen, I think you may be reading too much into Sunny 16. It's just a rule of thumb for estimating exposure. There can be no 'proof' of it per se -- no-one ever derived it -- and it's really just a happy coincidence that the exposure needed for a subject in full sun in middle latitudes is 1/ASA at f/16. There's nothing inherent in the ASA film speed standard that makes it so... it just works out that the denominator of the exposure needed (at f/16) on sunny days happens to be generally close to the numerical number we use to represent film speed.

 

Nothing fundamental about it. It only applies at middle latitudes. I remember reading something from a Scandinavian poster to the effect that he used something closer to a "Sunny f/11" rule.

The thing about people publishing theories is that you can test them out. Disprove them or prove them. It's really up to no one but you to prove the rule.

 

I have a theory the sun will come up in the east every morning. You can test this theory out yourself.

"Yes, but WHY does this work? I believe that settling for such a superficial answer can impede a deeper understanding of the process."

 

Used as a rule of thumb, it works because our sun is as bright as it is. Seems simple enough. And the rabbit hole goes all the way to the end, in case you are fretting about that too, Stephen. You are fond of testing, so go test it and make us a graph when you are finished ;^). (Try to make it simple, so I can understand it too.)

<I>Take an incident reading outside on a clear sunny day, and you should get f:16 at 1/ISO. </I></p>

Yes, but WHY does this work? I believe that settling for such a superficial answer can impede a deeper understanding of the process. Let's make this a substantive discussion. </p>

<b>Are you asking why a incident light meter yields the same EV value in the exact same lighting conditions (cloudless day) in two different locations? Or do you not understand the relationship between EV and exposure (f-stop and shutter speed)? If you don�t understand why that is, there is an appalling lack of understanding here that probably none of us can cure.</p>

 

Of course, in the real world, the lighting conditions on a sunny day are not identical in two different locations, since factors like latitude, time of year, humidity, etc do effect the amount of light falling on a scene even on a cloudless day. In addition, one might want to take into account the amount of shadow detail and contrast desired, which might vary between two different images.</b>

Stephen, like you, this was one of the first 'rules' that I learned when starting out in this hobby, and it's served me quite well for a number of years shooting mainly reversal material. I guess the rule works (for me) because it's always delivered the goods, with minor tweeking (cats/coal sheds etc). In fact, I always used the rule to calibrate my light meters and was rarely let down.

 

When I started getting more and more interested in B/W, however, this rule didn't prove so satisfactory. I always felt that the results were too muddy and underexposed but as the rule had always worked before, I never had the courage to question it. It wasn't until I started really looking at my results that I felt I had to fundamentally review my working habits with B/W. So I looked at my own work, and that of other photographers I admire, and concluded that I was underexposing by around a stop and a half. So I came up with my own version which is a sort of 'sunny f10'; that is, I expose Nepoan 400 souped in D/D23 at around 250th @ f11. Calibrating my meters to produce this result in bright sun gives me results that I am happy with about 70% of the time.

 

Is this the fault of the 'sunny 16' rule or does it say more about the ISO speed rating on B/W material? Maybe it's just that reversal and negative material just behaves differently or maybe it's just the cumulative effect of my equipment and my technique being different to someone elses. Stephen, the fact that you've come out and questioned the rule means you're more than half way there. Do your own tests and you'll come up with something that works for you which, after all, is what it's all about.

I always just figured that before there were light meters, our photographers had to come up with some sort of ball park exposure that was consistent. They, using incredibly slow films compared to our day, were more than likely doing mostly full sunny day exposures. After doing about a thousand guesses, I would imagine they found a rule of thumb. Just a guess on my part, but most rules have their basis in repeatable practices.

 

<br><br>however, since you wanted some sort of proof <a href="http://home.earthlink.net/~kitathome/LunarLight/moonlight_gallery/technique/attenuation.htm">this comes pretty close to proof</a><br>

THE PROOF IS IN THE PUDDING. - Why use pudding instead of custard?

 

It's just an easy way of describing to a *beginner* this particular method of dead reckoning for setting a manual exposure in daylight. f/16 just happens to be the aperture setting for a properly exposed negative when the recipricol of the film speed is used to set the shutter.

 

It ain't perfect, but the rule will provide for a workable exposure setting when using print film. You learn quickly the need to fine tune with regards to your subject. For example, I have a Sunny 11 Rule for dark colored subjects and Sunny 22 rule for highly reflective backgrounds.

 

NOT EVERY CAMERA HAS A WORKING LIGHT METER: Most of my cameras don't have built-in light meters. Also, I have a penchant for shooting at f/5.6 and f/8, but invariably the "Sunny 16 Rule" will get me where I need to be with regards to the proper shutter speed.

TO KELLY: Thanks for the photos. Many of my cameras use the latter LVS system, which seem to beyond comprehension to some younger photographers. EV 15 is my reference point in full sun for ISO 100 film, but at the time these cameras were made the same film was rated at ASA 50 and the recommended light value is EV14.

 

My Rolleicord V has a much different chart than the Rolleicord IV.

 

One of the more useful diagrams is the chart showing the length of the subject's shadow in relation to their height. It amazes me the thought that went into shadow diagram, because it isn't just for the time of day, but also serves as a reference for the sun's angle at a given lattitude with regards to the time of year.

I'm just trying to wake people up from their complacency. It seems that people can go on and on about developers, but seem to have nothing to say about concepts of exposure and tone reproduction. One is a tool, one is how to use the tool.

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Jean-Baptiste is on the right track with his average illumination statement, but the value of 320 footlamberts (not footcandles) isn't exactly correct. But he is right that it has something to do with average conditions and with how exposure is calculated? At first, I thought he was using circular logic, but not now. You know, it's f/16 because the meter says it's f/16. BTW, Jean-Baptiste, have you considered how it all relates to the variable P in the exposure formula?

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As for the others, it should be obvious that Sunny 16 only relates to average sunny conditions. Everything in exposure theory and tone reproduction is based on average conditions and the degree in which these conditions deviate.

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<i>it works because our sun is as bright as it is. Seems simple enough.</i>

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So does this have any connection with how film speed is calculated, or how meters are calibrated, or how the math was determined to define how everything interrelates. Could this seemingly simple concept be a product of the very complex and involved concepts of exposure theory?

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I'm not fretting anything. I know the theory behind Sunny 16. I'm just using the Socratic method to motivate people to reevalute what they think they understand. How secure are you on the issue? Are you able to come at it from a variety of directions? You can give someone the answers, but until they are ready, they will never recognize them.

Mr Don Norwood invented the photosphere/dome used in incident light meters in the 1930's. His patent 2,214,283 was filed in 1938; Was Patented in 1940; and ran out about 1960. The NORWOOD DIRECTOR meter of 1948 was a hit with the movie industry.

The ASA manual of mine is from 1948; from the "American Bolex company". Super-XX was an ASA of 100 then in daylight; like the Rollei backs above. Verichrome (ortho) was ASA 50.<BR><BR>The guide says to use your own testing. It also says the speed indexes only apply to fresh film. It also says to use more exposure with outdated film. It also says to do your own testing; with your own equipment and meter.

"I'm just trying to wake people up from their complacency".

 

That is a rather bold statement. Perhaps many of us would rather be making images and using the tools to make visual statements, rather than exercising mental gymanastics. Many of us can do the mental exercise, in fact i use a sunny f11 if the meter runs out of batteries as that is works for my equipment in my location and evironment. Does this mean i am right or wrong? Neither, I am using my tools in a manner that produces the results that i find satisfactory.

Perhaps Steven is Socrates reincarnated, or perhaps he is a troll. You decide.

STEPHEN: the fine tuning comes from experience. A beginner on an shooting towards the west on overcast afternoon is very unlikely to add two stops of exposure for a back lit subject. It is here where the proper use of an incident meter tells a very interesting story.

 

Using the ideal example of a sunny day, one soon discovers with an incident pointed towards the camera from the subject, that the Sunny 16 Rule isn't perfect. The light on a sunny afternoon in late December in the northern latitudes, for example, is about two stops less bright than the light on an August afternoon. Add a little bit of atmospheric pollution and results will vary.

 

As mentioned earlier, the Sunny 16 Rule is more or less a dead reckoning method. It is up to the photographer to fine tune it for various apertures and the direction light striking the subject.

 

KELLY: The Rolleicord V set to EV 15 reads at 125th of a second for an f/16 exposure. I wonder why it changed between models. Better coatings on the lenses maybe?

I'm with Ann. I can accept that some arbitrary decisions were

made in defining film speeds, and I understand how the

numbers play out so we have a nice, clever name like Sunny 16

for a general exposure guideline for sunny days. I can also

accept the thousands of reasonably accurate exposures I've

made (and the many millions that others have made) using the

Sunny 16 rule as sufficient proof that it works.

 

If you're looking for some profound, philosophical basis for a

belief in Sunny 16, I think you're wasting time and effort than

could be much better spent pondering how to improve your

photos.

It was working out to be a Sunny 69 but Kodak thought that wouldn't go down too well so they moved the Earth a bit further away from the Sun to make it Sunny 16 and not cause giggling in Photo 101... believe it or not! ;)

<i>If you're looking for some profound, philosophical basis for a belief in Sunny 16, I think you're wasting time and effort than could be much better spent pondering how to improve your photos.</i>

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Obviously, I took the wrong approach with this thread. I got some people to think about how important tone reproduction is on the Over Exposure - anecdotal Vs objective analysis thread and I got hopeful.

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My apologies to Ann, I used the wrong choice of words.

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I don't understand people using the time better spent shooting argument on a technical forum. It's here to discuss technical issues. If you feel time is better spent shooting, why are you here?

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BTW, the time well spent in evaluating the causal reason for such things as Sunny 16 has allowed me to write the program that produces the tone reproduction curves which have in turn answered many fundamental questions about photography. Never discard anything out-of-hand.