Do You Know About the Sunny 16 Rule?

An exposure such as this is easy if you understand the Sunny 16 Rule.  No light meter needed.

Us old time film shooters, who used to use cameras that were either totally manual, had no light meter or only a small battery to power a basic light meter, will remember the Sunny 16 rule.  You may or may not know about it.

What is it?  Can it be useful to you?  Should you know it and understand it?  How about an expansion of it to better understand light and exposure?  Read on if you are interested in maybe saving your images.

The Sunny 16 Rule was created as an easy way for photographers to figure correct exposure, better understand exposure in differing circumstances and make good exposures under a variety of adverse circumstances.  Those circumstances include:

a)  you may not have a light meter with you,
b) your camera's light meter has malfunctioned,
c) your battery in your camera has died and your light meter has no power, and
d) you light meter might just be fooled by the lighting conditions, or
e) your subject's reflectance/tone can cause the light meter to give you an erroneous exposure.

The basic premise is that with film (it also applies to digital exposures) the correct exposure for a sunny day with the sun at your back (front lighting) will be 1/film's ISO @ f/16.  As an example, if you are shooting with ISO 100 film, or with your digital camera set to ISO 100, on a sunny day, with the sun behind you, your basic exposure for an average scene, is 1/100th second @ f/16.  Note I said average scene as there are some exceptions.  You can then vary the shutter speed/aperture combination as necessary to achieve the best result, according to your needs.

(Additionally, some meters in digital cameras may be calibrated slightly differently than other meters, so it would be wise to run a check to see if your exposures are dead on with these settings.  If too bright or too dark, you know your meter is calibrated differently and you have to make the mental adjustments.)

From that basic exposure, experienced photographers could calculate how many f/stops they would have to open their aperture if the scene varied from that basic exposure.  For example, if there was a very light cloud layer which caused the shadows to soften somewhat, you would open your aperture 1 stop.  If it was a cloudy but still bright day, with no distinct shadows, you open your aperture 2 stops. Other examples are that if the subject is lit from the side, open 1 stop.  Lit from the back (sun behind your subject)?  Open 2 stops.  And so on and so on.  With time, effort and experience, a photographer could remember these basic settings.  You can substitute changing shutter speeds instead of changing apertures, if you are photographing moving objects.

Here is some reference material that I dug out of my "ancient photographic materials" archives.  This kind of information was pretty readily available way back when but is largely unknown in this sophisticated digital age.  But you may find it useful.

Robert Harris produced a small $5.95 US device called the Harris Memory Meter.  On one side it had a circular rotatable calculator and the other contained narratives which would give the photographer a basic guide for exposure under differing circumstances.  By using the narratives to understand typical conditions, you could then use the calculator to figure your basic exposure for those conditions.

Below, with full credit to Mr. Harris, I have reproduced the narrative section to illustrate the differing conditions and how many stops you would open or close your aperture (with X representing your Sunny 16 setting), keeping your shutter speed at 1/ISO (again or any combination to equal the exposures)

From the Harris Memory Meter II, ©Robert S. Harris, 1982 (Reproduced Here)

The real usefulness for these types of formulas today is to understand light and exposure and how they translate to camera settings.

It is not unusual for your subject to fool your in-camera light meter into giving you an exposure that is wrong for the subject.  The subject may be predominantly dark, light, reflective, in sun but in front of dark shade, etc.  If you understand the basic rules of exposure, you can be assured of coming home with images that will be correctly exposed and give you the best quality file with which to work.

Also, as I have written in the past, exposure meters want to make everything a middle tone.  That is the very nature of them.  So, they will make white snow gray and make a wet black rock also gray.  If you understand the basics and exert some effort to remember those basics, your meter won't fool you and you won't miss that terrific shot you see before you due to a bad exposure.

Thanks for looking.  Enjoy!

Dennis Mook

Many of my images can be found at www.dennismook.com.  Please pay it a visit.  I add new images regularly.  Thank you.


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