Thursday, July 1, 2010

Sunny 16 aperture, shutter, ISO guide

Good guide to sunny day aperture settings from Wikipedia.

The basic guide to photography exposure is very simple. If you have a bright, sunny day, then use f-stop 16 for your camera lens aperture. The shutter speed should then be set to the equivalent of your ISO film speed – or the next number over. For example, if you are using an ISO film speed of 100, your shutter speed should be set to 1/125. More than often, your shutter speed number will be higher than the ISO film speed, but it is much easier to remember that film speed equals shutter speed.

The Sunny 16 rule can also help to determine aperture and shutter speed settings when conditions are not typical sunny days. For example, a hazy sun will require you to close one stop to f/11 while an overcast day would require f/5.6. Normally, changing the f-stop would require you to also change your shutter speed to ensure an even exposure. With the Sunny 16 rule, disregard that. Simply remember to keep you shutter speed set to the film speed ISO and the aperture to the amount of sun available.

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 f/16 and shutter speed to the [reciprocal of the] ISO film speed."[1] For example:
  • On a sunny day and with ISO 100 film in the camera, one sets the aperture to f/16 and the shutter speed to 1/100 or 1/125 second (on most cameras 1/125 second is the available setting nearest to 1/100 second).
  • On a sunny day with ISO 200 film and aperture at f/16, set shutter speed to 1/200 or 1/250.
  • On a sunny day with ISO 400 film 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.
An elaborated form of the Sunny 16 rule is to set shutter speed nearest to the reciprocal of the ISO film speed and f-number according to this table:[2][3]
Aperture Lighting Conditions Shadow Detail
f/22 Snow/Sand Dark with sharp edges
f/16 Sunny Distinct
f/11 Slight Overcast Soft around edges
f/8 Overcast Barely visible
f/5.6 Heavy Overcast No shadows
f/4 Open Shade/Sunset No shadows
Add One Stop Backlighting n/a

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