How to use the calculator

Choose what to calculate, then select the other three values. For example, keep EV 15 · Sunny 16, ISO 100, and f/16 to get a shutter speed near 1/125 second. Switch to calculating aperture to choose a shutter speed yourself. Choose EV from camera settings to find the light level that a combination corresponds to.

The disabled dropdown shows the nearest available setting. The result includes the calculated value and the exposure difference caused by rounding. The available ISO, aperture and shutter values are common camera settings; your camera or lens may have a smaller range.

What is Sunny 16?

For a subject in direct, bright sunlight, start at f/16 with a shutter time around 1/ISO seconds: ISO 100 suggests 1/100 second, and ISO 400 suggests 1/400 second. Cameras with traditional full-stop shutter dials commonly use the nearby 1/125 or 1/500 second settings.

This calculator uses EV 15 at ISO 100 as the rounded Sunny 16 preset. The literal f/16 and 1/100 second rule corresponds to EV100 ≈ 14.64. At EV 15, f/16 and ISO 100 calculate to 1/128 second, with 1/125 second the nearest dropdown setting. These are approximate outdoor starting points, rather than a guarantee of the right exposure for every subject.

Hazy sun, cloudy skies and shade presets suggest progressively lower light levels. The descriptions are rough estimates: time of day, latitude, subject reflectance and the direction of the light all matter. Use a meter or test image when possible, especially for backlit subjects or scenes with bright highlights.

Understanding EV and equivalent exposure

Here EV means EV100: a light level referenced to ISO 100. It stays fixed when you change ISO and calculate a matching shutter speed or aperture. A one-stop increase in EV represents twice the scene light, so it calls for half as much exposure at the same ISO.

The relationship used is:

EV100 = log₂(aperture² / shutter time in seconds) − log₂(ISO / 100)

Doubling ISO lets you halve the shutter time while keeping the aperture and scene light level unchanged, as illustrated in Nikon’s guide to ISO sensitivity. Opening the aperture by one full stop also lets you halve the shutter time. Nominal camera labels such as f/2.8 and 1/125 are rounded, so calculations can differ slightly from perfect one-stop steps.

The calculator models continuous light without flash, filters, exposure compensation or film reciprocity failure. For long exposures on film, follow the film manufacturer’s reciprocity guidance. For digital cameras, check the histogram and adjust for your desired rendering.