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The sunny 16 rule in photography

Today I read an electronic book on photography, especially on the understanding of the depth of field. In the book there is a word that interests me to know more about the terminology in photography.

The word was Sunny 16. And what is 'Sunny 16'? The Sunny 16 is a method of estimating correct daylight exposures without a light meter.

It simply means that from the book told me, when the sun is shining, a correct exposure of a front-lit scene will be found at f/16 and at a shutter speed that equals your ISO, e.g. with 100 ISO the correct exposure is f/16 at a 1/125 second and as long as it is 90 minutes after sunrise and 90 minutes before sunset.

The sunny 16 rule basically says if you're outside on sunny day, set your camera to f/16, your shutter speed to 1/125th and shoot, your photos should appear well exposed and sharp front to back.

Without light meter

Then i took my camera on the shelf. Turning on the power button , set dial mode to "M" then adjust the shutter speed and f number to the correct as the book says (1/125th and f/16). Try to look at the viewfinder, aiming some object , and shoot.

Back in to my first paragraph, "The Sunny 16 is a method of estimating correct daylight exposures without a light meter". So why we have to learn the sunny 16 rule if we have a light meter built in inside the camera ?

That is a critical question for me. Basically this rule are provided in old SLR cameras. But at the new age, its a basic to learn and improving photographer instinct about light condition and what the best camera setting to make better images.

In my opinion, this sunny 16 rule is an automatic setting for photographer can do. It just like an Auto mode in Digital slr camera.

For example if you are using Auto mode, the camera will find the fine logical exposure for the image that you want to shoot (the exposure parameters are inside the camera's computer and computed from light meter basic value), and so the sunny 16 rule for photographers.

It would bring the auto setting behavior for the light condition in every photographers mind, and the basic value are learned from the sunny 16 rule.

Let's take a look for The Sunny 16 Rule


Sunny 16 rule

The sunny 16 rule that i copied from wikipedia.org/free ensiclopedia :

The basic rule is, "On a sunny day set aperture to f/16 and shutter speed to the [reciprocal of the] ISO film speed [or ISO setting] for a subject in direct sunlight."

For example:
  • On a sunny day and with ISO 100 film / setting in the camera, one sets the aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on some cameras 1/125 second is the available setting nearest to 1/100 second).
  • On a sunny day with ISO 200 film / setting and aperture at f/16, set shutter speed to 1/200 or 1/250.
  • On a sunny day with ISO 400 film / setting and aperture at f/16, set shutter speed to 1/400 or 1/500.


As with other light readings, shutter speed can be changed as long as the f-number is altered to compensate, e.g. 1/250 second at f/11 gives equivalent exposure to 1/125 second at f/16.

More in general, the adjustment is done such that for each step in aperture increase (i.e., decreasing the f-number), the exposure time has to be halved (or equivalently, the shutter speed doubled), and vice versa.

This follows the more general rule derived from the mathematical relationship between aperture and exposure time  within reasonable ranges, exposure is proportional to the square of the aperture ratio and proportional to exposure time;

Thus, to maintain a constant level of exposure, a change in aperture by a factor c requires a change in exposure time by a factor 1/c² and vice-versa. Steps in the aperture always correspond to a factor close to the square root of 2, thus the above rule.

Here you can uses the following table to get the right suggested settings on the f number and ISO in various lighting conditions.

Sunny 16 suggested settings

Just remember, if you change the f-stop adjust the shutter speed accordingly. so if you open the lens by one full f-number, the shutter speed needs to be cut in half, and visa versa.

Well, the result of all images is depend on how often you became seriously to learn photography in every time you take a shoot. Just Shoot more and learn, have a nice day :)