What is the exposure triangle?

The exposure triangle describes the relationship between aperture, shutter speed, and ISO. These three settings control how much light reaches the sensor. Changing one requires compensating with one or both of the others to maintain the same exposure.

What is an Exposure Value (EV)?

EV is a single number representing a combination of aperture and shutter speed. EV 0 equals f/1 at 1 second at ISO 100. Each increase of 1 EV halves the light. Bright sunlight is around EV 15, while a dimly lit room might be EV 5-7.

How do I choose which setting to solve for?

It depends on your creative priority. If you need a specific depth of field, lock aperture and solve for shutter or ISO. If you need to freeze motion, lock shutter speed. If you want the cleanest image, lock ISO to its lowest value and solve for the others.

Does ISO really affect exposure?

ISO amplifies the sensor signal after light capture. It does not change the amount of light hitting the sensor (that is controlled by aperture and shutter speed), but it changes the brightness of the resulting image. Higher ISO introduces more noise.

PhotoCalcs

Exposure Triangle Calculator — Balance Aperture, Shutter & ISO

Calculate the missing exposure setting when you know the other two and your target exposure value.

Solve For

Which setting do you want to calculate?

Target EV

EV 12-16 for daylight, 5-9 indoors

Aperture

ISO

How We Calculate This

The exposure triangle calculator uses the fundamental photographic exposure equation:

EV = log2(N² / t) at ISO 100

Where N is the f-number (aperture) and t is the shutter speed in seconds. For other ISO values, the adjusted EV is:

EV_adjusted = EV + log2(ISO / 100)

Given a target EV and two of the three settings, the calculator solves for the third. For example, to find shutter speed: t = N² / (2^EV × ISO/100).

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.