Sunny 16 rule
Encyclopedia
In photography, the Sunny 16 rule (also known as the Sunny f/16 rule) is a method of estimating correct daylight exposures
without a light meter
. Apart from the obvious advantage of independence from a light meter, the Sunny 16 rule can also aid in achieving correct exposure of difficult subjects. As the rule is based on incident light, rather than reflected light as with most camera light meters, very bright or very dark subjects are compensated for. The rule serves as a mnemonic
for the camera settings obtained on a sunny day using the exposure value
(EV) system.
The basic rule is, "On a sunny day set aperture
to and shutter speed
to the [reciprocal of the] ISO film speed
[or ISO setting] for a subject in direct sunlight." For example:
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.
An elaborated form of the Sunny 16 rule is to set shutter speed
nearest to the reciprocal of the ISO film speed
/ setting and f-number
according to this table:
! Aperture
! Lighting Conditions
! Shadow Detail
|-
| 22
| Snow/Sand
| Dark with sharp edges
|-
| 16
| Sunny
| Distinct
|-
| 11
| Slight Overcast
| Soft around edges
|-
| 8
| Overcast
| Barely visible
|-
| 5.6
| Heavy Overcast
| No shadows
|-
| 4
| Open Shade/Sunset
| No shadows
|-
| Add One Stop
| Backlighting
| n/a
|}
Exposure (photography)
In photography, exposure is the total amount of light allowed to fall on the photographic medium during the process of taking a photograph. Exposure is measured in lux seconds, and can be computed from exposure value and scene luminance over a specified area.In photographic jargon, an exposure...
without a light meter
Light meter
A light meter is a device used to measure the amount of light. In photography, a light meter is often used to determine the proper exposure for a photograph...
. Apart from the obvious advantage of independence from a light meter, the Sunny 16 rule can also aid in achieving correct exposure of difficult subjects. As the rule is based on incident light, rather than reflected light as with most camera light meters, very bright or very dark subjects are compensated for. The rule serves as a mnemonic
Mnemonic
A mnemonic , or mnemonic device, is any learning technique that aids memory. To improve long term memory, mnemonic systems are used to make memorization easier. Commonly encountered mnemonics are often verbal, such as a very short poem or a special word used to help a person remember something,...
for the camera settings obtained on a sunny day using the exposure value
Exposure value
In photography, exposure value denotes all combinations of a camera's shutter speed and relative aperture that give the same exposure. In an attempt to simplify choosing among combinations of equivalent camera settings, the concept was developed by the German shutter manufacturer in the 1950s...
(EV) system.
The basic rule is, "On a sunny day set aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...
to and shutter speed
Shutter speed
In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a camera's shutter is open....
to the [reciprocal of the] ISO film speed
Film speed
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system....
[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.
An elaborated form of the Sunny 16 rule is to set shutter speed
Shutter speed
In photography, shutter speed is a common term used to discuss exposure time, the effective length of time a camera's shutter is open....
nearest to the reciprocal of the ISO film speed
Film speed
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system....
/ setting and f-number
F-number
In optics, the f-number of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter...
according to this table:
-
- {| border="1" cellpadding="5" style="border-collapse: collapse;"
! Aperture
F-number
In optics, the f-number of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter...
! Lighting Conditions
! Shadow Detail
|-
| 22
| Snow/Sand
| Dark with sharp edges
|-
| 16
| Sunny
| Distinct
|-
| 11
| Slight Overcast
| Soft around edges
|-
| 8
| Overcast
| Barely visible
|-
| 5.6
| Heavy Overcast
| No shadows
|-
| 4
| Open Shade/Sunset
| No shadows
|-
| Add One Stop
| Backlighting
| n/a
|}
External links
- Guide to Photography Sunny 16 and film exposure guide.
- Ultimate Exposure Computer Fred Parker's guide to using the Sunny 16 Rule and an EV scale to calculate exposure by hand.
- Rules of thumb for moonlit exposures