Sunny 16 Rule: Estimating Exposure Outdoors

pathfinder

Estimating Proper Exposure without a Light Meter Out of Doors


Some new digital photographers seem to have difficulty believing that you can shoot a digital camera in manual mode outdoors for most of the daylight hours without using a light meter. After all, new digital cameras all have light meters and automatic exposure modes built into them.
But 70 years ago, folks were shooting Kodachrome transparency film without any light meters. Kodak's Kodachrome was very intolerant of incorrect exposure. Modern digital cameras are similar in their requirements for correct exposure, but may be more forgiving than Kodachrome.

I did a review of “Bound for Glory - American Color 1939-1943” - a book full of images of Kodchrome that were probably shot without a light meter. Kodachrome is very unforgiving of improper exposure - maybe 1/2 stop of light too little or too much and the slide was ruined.

This was shot in 1945 without a light meter - I know, because this is shot of your author age 1 in Fort Sam Houston Texas.


The focus wasn’t too good, but the exposure wasn’t off by much. How did my father do that??
Rather than a light meter, he almost certainly used the rule known as the “Sunny 16”, which lets you estimate the exposure between 10 am and 5 pm accurately, without a light meter. You might ask why this is worth wasting your time on today when you already own a excellent meter in your camera.

The answer is that, even today, meters can give the wrong exposures, and it is always good to be able to estimate the correct exposure in your head without any tools but the understanding of the Sunny 16 rule.

Light meters get fooled when asked to meter very bright objects such as a snow covered landscapes, or a shot of the moon, or a very dark object like a black labrador retriever. The reason meters get confused is that they assume everything in the area metered is a neutral mid range tone and then read its reflectance - the so called 16% grey card, but in the real world things are not always medium tones.

The sunny 16 rule is based on INCIDENCE lighting, and will frequently be more accurate than most reflected meter readings that depend on the reflectance of the subjects. Incident metering does not depend on the subject, only the intensity of the lighting.

The Sunny 16 rule is based on the fact that the sun is equally bright everywhere outdoors between 10 am and 5 pm. So, if you know what the exposure is for sunlight at mid-day, then you can estimate it for cloudy or overcast situations.

The rule states that the proper exposure is determined by the ISO of the film/sensor setting. We will assume ISO 100. For ISO 100, at mid day with sunlit mid-toned object, set the aperture at f16, and the shutter speed at 1/ISO or 1/100th ( if your camera does not have a shutter speed of 1/100th, a setting of 1/125 if good enough for government work.)

(Mod edit: Removed color, applied Boldface instead.)

Knowing this basic exposure allows us to draw up the following table based on exposure values


Notice that the table shows values for ISO 100, 200, and 400. If you have ISO 1600, then f16 at 1/1600th is the correct exposure. Then, by equivalencies, the rest of the table can be constructed

f16 1/1600
f11 1/3200
f8 1/6500
f5.6 1/13000

But there are no consumer cameras with shutter speeds this high, so you will need to dial back the ISO in bright sunlight.

But, what if the day is not bright sunlight, but cloudy?? Then, the light is described by the shadows seen, or not seen.

Soft shadows, easily seen with soft edges is weak, hazy sunlight and needs 1 stop more light or f11 rather than f16 at 1/ISO.

Cloudy bright days refer to days where shadows are barely visible, and they require 2 stops more light or f8 and 1/ISO.

Overcast means NO SHADOWS and requires 3 stops more light or f5.6, the same as in the shade on a sunny day.

This knowledge can be very helpful.
One example that comes up frequently, is people trying to shoot shots of the moon. They point their camera, in an automatic mode, at a black sky with a small, bright, white moon, and find out that the moon is not exposed correctly at all.

The moon is a sun lit object - just like a car sitting on the street at noon - and the exposure should be very close to the same even though the moon is very distant.

So, for ISO 100, the settting would be f16 at 1/100th. Or we could open the aperture two fstops, f16->f11->f8 , and shorten the shutter speed up two stops 1/100th->1/200th ->1/400th and shoot at f8.0 at 1/400th at ISO 100.
I found this image I shot last fall in my gallery.



Note the exposure data - ISO 100 f8.0 1/400th - Guess how I chose those settings???...
Just as predicted by the Sunny 16 rule. Now does this seem worthwhile to know??

Here are a couple more examples I have just pulled randomly from my galleries.

Here is an image that is hard for meters do deal with - bright, sunlit snow. - Indeed, I dialed in +1.33 Exposure compensation to help the meter read this scene - and it was metered and shot at f11.0 at 1/40th at ISO 100. Sunny 16 would give f11, 1/50 at ISO 100 for objects in an overcast sky. This image is confusing at first, because f11 at 1/50th is two whole stops faster than required for a sunlit object. But the skier's faces are NOT SUNLIT, the faces are in the shade, and shaded objects require 3 stops more than sunlit. I actually only gave two stops more exposure due to the high reflectance from the surrounding snow. SO - shadowed subjects f11 ISO 100 1/50th is pretty good in the snow.



Here is another very brightly lit snow field at 10,00 feet - not a cloud in the sky
EXF data -> f8.0 1/500th at ISO 100 Sunny 16 -> f8.0 1/400th at ISO 100 - pretty close




Here is another image - shot in a cloudy day with barely visible shadows calling for 2 stops more light than bright sunshine at 7500 feet in Wyoming

EXIF-> ISO 400 f5.6 1/1000th Sunny 16 suggests two stops more light than sunshine or f8 at 1/400th for ISO 400, or f5.6 at 1/800th Again - pretty close!!


Again, the horse's shadow is barely visible, shot at 7000 feet in Wyoming,- add two stops - EXIF -> ISO 400 f11 1/200th Sunny 16 suggests ISO 400 f11 1/200th Again it seems to work .


I hope I have demonstrated that the Sunny 16 rule is easy to understand, and can be very helpful in understanding exposures needed and in intepreting your cameras exposures properly.

ThatCanonGuy

There's a t-shirt for this rule!:D

pathfinder

i wish i had thought of that!

babowc

I did not know of this and this is great! I will try this on the next sunny day.

ziggy53

thumb

zoomer

Click once check blinkies and histogram ..adjust exposure if necessary...confirm adjustments with second click. Good to go. Takes about 5 seconds.
Welcome to the digital world .
People who do understand exposure and have all this knowledge....I give a virtual bow to.
Shooting film required so much knowledge in this area....I imagine with lots of experience it all became second nature and could be eyeballed.

Moving Pictures

zoomer wrote: »

Click once check blinkies and histogram ..adjust exposure if necessary...confirm adjustments with second click. Good to go. Takes about 5 seconds.
Welcome to the digital world .
People who do understand exposure and have all this knowledge....I give a virtual bow to.
Shooting film required so much knowledge in this area....I imagine with lots of experience it all became second nature and could be eyeballed.

Living in Canada, I end up capturing a fair number of snow-type pics, which as the OP states, does confound most built-in meters. I noted the OP suggested exposure compensation, but my trick is to simply set the camera to over-expose by 2/3 stop ... which usually does it.

Like you said, "check blinkies and histogram."

pathfinder

If shooting in Av, Tv, or Auto, one uses Exposure Compensation to adjust meter readings in very bright, and very dark scenes, since the meter will automatically try to render them as a mid tone grey.

If shooting in Manual Mode, which is what I would recommend for using Sunny 16, then there is no Exposure Compensation, but merely the shooter's chosen exposure. For shooting snow + 2/3 to + 1.5 stops is used by many folks.

rpcrowe

In the days of Kodachrome
In the days of Kodachrome, most professional photographers knew the "Rule of Sunny 16" but, most professionals also used a meter to help determine their exposure.

Additionally, many professional photographers bracketed their exposures so that they would be sure of getting a usable shot. Few non-professionals could bracket because it increased the cost of film and processing by 300 per cent.

Bracketing in those days was not as easy as with today's DSLR cameras. The photographer had to manually change the exposure for each shot which could be a PITA.

Today, using Canon DSLR cameras (I don't know about other brands) bracketing is absolutely simple. Just select AEB, decide on how many stops you desire to bracket by and place your camera on burst mode.

Press the shutter and the camera will shoot three bracketed exposures and then stop shooting. Absolutely no pain! It doesn't cost any more than shooting single shots and ensures that you will get a great exposure.

When using AEB, I suggest that the photographer select the menu option which will continue AEB after the camera is shut down and turned on again; rather than the default of reverting away from AEB to standard exposure when the camera is shut down.

BTW: when guestimating the exposure using the "Rule of Sunny 16" compensation for bright and dark subjects is different than compensating for the camera reflected meter's reading. It is actually the reverse!

Using the Sunny 16 Rule, you decrease the exposure for bright and increase the exposure for dark subjects.

Compensating for the camera's meter reading, you increase exposure for bright subjects like snow and decrease exposure for dark subjects like a black cat in a coal bin...

arodney

IF film and raw exposure (or raw expsoure and JPEG expsoure which tries to mimic film) were ideal, we could use this kind of process. They are not. If you expose properly for that JPEG (or film), you are very often under exposing for optimal raw data (Expose to the right or ETTR). If you don’t mind more noise, then handle raw and film or raw and JPEG the same. IF you compensate for exposure of raw with this understanding, then you could use the Sunny 16 rule (use it, open up X number of stops based on testing your sensor for ETTR).

ziggy53

It's vital to understand what each camera's meter and histogram means, with respect to your use of the camera and your intentions for the image. It's rather hard to find cameras that meter the same as ISO sensitivity standards, and there are more than one ISO metering standard as well.

Arodney's point is especially pertinent in scenes with low dynamic range. In those situations the "Expose To The Right" method works much better than a "standard" exposure. The reasons are described here:

http://www.luminous-landscape.com/tutorials/expose-right.shtml

For scenes with normal to high dynamic range I use the "Protect Important Highlights" rule, which means to personally evaluate the scene and determine which, if any, highlights may be "bleached" (i.e. devoid of sufficient color to allow for recovery in post-processing.)

Today's RAW image processing software actually do a fairly good job of "inventing" or guessing missing color channel data during highlight recovery, within reason. Understand the limits of highlight recovery in your software and use every nuance of the RAW highlight recovery abilities if the dynamic range of the scene is very broad and if you also need detail in the deep shadows.

For static scenes and using a tripod, multiple bracketed exposures, suggested by Rpcrowe, are indeed a valid procedure and method. Either HDR or tone-blending can be used to work the available bracketed tones back into something usable, or something artistic, in a single image.

I do agree that the "Sunny 16" rule, used properly and tempered with experience and judgement, works as well today as ever (until our Sun changes its luminosity and/or our Earth changes its usage of sunlight, neither of which should occur in our lifetime.) If nothing else, it makes an excellent starting point if you have no other method available.

pathfinder

When I wrote this thread over 6 years ago, I did not mean one should never use a meter, or not expose to the right.

I was merely trying to get folks to appreciate that over 70 years ago folks shot Kodachrome, with its very narrow exposure range, without light meters, rather successfully with Sunny 16, which is based on the fact that the Sun's luminosity does not change during daylight hours. If one has a basic understanding of Sunny 16, and your light meter gives a reading 2 or 3 stops different, it is worth one's while to examine if that reading is really accurate, or as good as Sunny 16's preferred exposure.

I do use Lightroom 4, and truly value the ability to pull out shadow detail, and decrease noise with exposure to the right, especially when I shoot RAW, which is most of the time. But not ALL of the time, as sometimes the ease and simplicity of jpgs is worthwhile. But jpgs have even a narrower exposure latitude than shooting RAW files.

I always say that real pro's know many more ways, than just one way, to skin a cat.