Exposure Triangle Calculator
Calculate correct exposure settings balancing aperture, shutter speed, and ISO. Enter values for instant results with step-by-step formulas.
Reviewed by Daniel Agrici, Founder & Lead Developer
Formula
EV = log2(f-number^2 / shutter speed) - log2(ISO / 100)
Exposure Value (EV) is calculated from the f-number (aperture), shutter speed in seconds, and ISO sensitivity. Equivalent exposures have the same EV value. Changing one parameter by one stop requires compensating with another parameter by one stop in the opposite direction.
Worked Examples
Example 1: Portrait: Switching from Sharp to Blurry Background
Problem:Current settings: f/5.6, 1/125s, ISO 100. You want to shoot at f/2.8 for background blur. What shutter speed is needed?
Solution:Aperture change: f/5.6 to f/2.8 = +2 stops of light\nTo compensate, increase shutter speed by 2 stops\n1/125s + 2 stops = 1/500s\nCalculation: new SS = (2.8^2 x (1/125) x 100) / (5.6^2 x 100)\n= (7.84 x 0.008) / 31.36 = 0.002 = 1/500s
Result:New settings: f/2.8, 1/500s, ISO 100 (equivalent exposure)
Example 2: Indoor Event: Compensating for Low Light
Problem:Current settings: f/4, 1/125s, ISO 100. Image is 3 stops underexposed. What ISO is needed to keep the same aperture and shutter speed?
Solution:Need 3 stops more light via ISO\nISO 100 + 1 stop = ISO 200\nISO 200 + 1 stop = ISO 400\nISO 400 + 1 stop = ISO 800\nEach doubling of ISO adds one stop of sensitivity
Result:New settings: f/4, 1/125s, ISO 800 (3 stops brighter)
Frequently Asked Questions
What is the exposure triangle in photography?
The exposure triangle is a fundamental photography concept describing the relationship between three camera settings that control how much light reaches the sensor: aperture, shutter speed, and ISO. These three elements work together to determine the overall exposure (brightness) of an image. Changing one setting requires compensating with one or both of the others to maintain the same exposure level. For example, opening the aperture by one stop lets in twice as much light, which can be compensated by doubling the shutter speed or halving the ISO. Mastering this triangle is essential for creative control over depth of field, motion blur, and image noise.
How does aperture affect exposure and depth of field?
Aperture is the size of the lens opening, measured in f-stops (f/1.4, f/2.8, f/5.6, etc.). A lower f-number means a wider opening that lets in more light and produces a shallower depth of field (blurry background). A higher f-number means a narrower opening with less light but greater depth of field (more of the scene in focus). Each full f-stop change doubles or halves the light. The common full-stop aperture sequence is f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16. Portrait photographers typically use wide apertures (f/1.4 to f/2.8) for background blur, while landscape photographers use narrow apertures (f/8 to f/16) for front-to-back sharpness.
What is an EV (Exposure Value) stop and how are stops counted?
An EV stop is a standardized unit representing a doubling or halving of the amount of light reaching the camera sensor. One stop brighter means twice the light; one stop darker means half the light. Each of the three triangle elements uses stops: aperture changes by one stop when the f-number is multiplied or divided by the square root of 2 (approximately 1.414). Shutter speed changes by one stop when doubled or halved. ISO changes by one stop when doubled or halved. Most modern cameras allow adjustments in 1/3 stop increments for finer control. Understanding stops makes it easy to compensate between settings while maintaining equivalent exposure.
What are the best exposure settings for common photography scenarios?
For portraits, use f/1.4 to f/2.8 for background blur, 1/125s or faster to avoid motion blur, and ISO 100-400. For landscapes, use f/8 to f/11 for maximum sharpness, any shutter speed with a tripod, and ISO 100. For sports and action, use the widest aperture available, 1/500s or faster, and increase ISO as needed. For night photography, use f/2.8 or wider, 15-30 seconds on a tripod, and ISO 1600-6400. For indoor events, use f/2.8 or wider, 1/60s minimum, and ISO 800-3200. These are starting points that you should adjust based on your specific conditions, creative intent, and equipment capabilities.
References
Reviewed by Daniel Agrici, Founder & Lead Developer · Editorial policy