A single number representing scene brightness. EV 15 = bright sun, EV 0 = dim indoors.

How do I calculate exposure manually?

Sunny 16 rule: at f/16, shutter = 1/ISO. Adjust in stops from there.

Photography

Exposure Calculator

Calculate EV from camera settings, determine shutter speed with ND filters, and correct for reciprocity failure in long exposures.

Quick Answer

EV = log₂(f²/t) at ISO 100. Each stop of ND filter doubles the required shutter speed. A 6-stop ND turns 1/125s into 0.5s. A 10-stop ND turns 1/125s into 8s.

Mode

Aperture (f/)

Shutter Speed

ISO

Results

EV 11.9

Exposure Value (ISO 100)

9.8k lux

Approximate Illuminance

About This Tool

The Exposure Calculator is a three-in-one photography tool. The EV calculator determines the exposure value from your camera settings. The ND filter calculator shows what shutter speed you need when adding a neutral density filter. The reciprocity calculator corrects for reciprocity failure in long exposures with film.

Exposure Value Explained

Exposure Value (EV) is a number that represents a combination of shutter speed and aperture. EV 0 at ISO 100 corresponds to an exposure of 1 second at f/1.0. Each increment of 1 EV halves the light (one stop brighter scene). Bright sunlight is about EV 15. A typical office is EV 7-8. Moonlight is around EV -2.

ND Filter Photography

Neutral density filters reduce the amount of light entering the lens without changing colors. They allow you to use slow shutter speeds in bright conditions for effects like silky water and motion blur in clouds. A 6-stop ND filter is the most versatile, while a 10-stop filter enables multi-minute exposures even in daylight.

Reciprocity Failure

Film becomes less sensitive during long exposures, a phenomenon called reciprocity failure. At exposures beyond about 1 second, you need to add extra time to compensate. The amount varies by film stock. This calculator uses an exponent of 1.3, which is typical for many films. Digital sensors do not suffer from reciprocity failure, so this correction only applies to film photography.

The Exposure Triangle

Aperture, shutter speed, and ISO form the exposure triangle. Each controls both exposure and a creative effect: aperture controls depth of field, shutter speed controls motion blur, and ISO controls noise. A proper exposure can be achieved with many different combinations of these three settings, and choosing the right combination depends on your creative intent.

Frequently Asked Questions

What does EV (exposure value) mean?

EV is a single number representing the brightness of a scene and the camera settings needed to capture it. Higher EV means brighter. EV 15 is bright sunlight, EV 0 is very dim indoor lighting. Each full EV increment represents one stop of light.

How do ND filters work?

ND filters are like sunglasses for your lens. They reduce incoming light by a specified number of stops without affecting color. This lets you use wider apertures or slower shutter speeds in bright conditions. A 6-stop ND lets you shoot a 1-second exposure where you'd normally need 1/60s.

What ND filter should I buy first?

A 6-stop ND filter is the most versatile starting point. It's dark enough for daytime long exposures (1-4 seconds for water effects) without being so extreme that focusing becomes difficult. A variable ND (2-5 stops) is great for video. Consider a 10-stop for dramatic multi-minute exposures.

What is reciprocity failure?

Film chemistry becomes less efficient at very long exposures. A metered 10-second exposure might actually need 20 or 30 seconds on film. Each film stock has its own reciprocity characteristics. Digital sensors don't have this issue, though they do accumulate more noise in long exposures.

How do I calculate the correct exposure manually?

Start with the sunny 16 rule: on a sunny day at f/16, the shutter speed equals 1/ISO. So at ISO 100, use f/16 at 1/100s. From there, adjust in stops. Opening one stop (f/11) means you need one stop faster shutter (1/200s). Each stop doubles or halves the light.

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