Understanding the Exposure Triangle
Calculate equivalent exposures in photography.
In photography, Exposure is determined by three interconnected settings: Aperture, Shutter Speed, and ISO. This is universally known as the Exposure Triangle.
If you change one setting—for example, if you want a faster shutter speed to freeze motion—you must counterbalance it by changing one or both of the other settings to let in the exact same amount of light. Our calculator does the underlying math (Exposure Value / EV100 calculation) to find the exact equivalent exposure instantly.
The Three Pillars of Exposure
Aperture (f-stop)
Controls the physical size of the opening in the lens. Lower numbers (f/1.4, f/1.8) mean a wider opening, letting in more light. Higher numbers (f/11, f/16) mean a smaller opening.
Side Effect: Depth of Field. Low f-stops blur the background (bokeh), while high f-stops keep both foreground and background in focus.Shutter Speed
Controls the amount of time the camera sensor is exposed to light. Faster speeds (1/1000s) let in less light. Slower speeds (1" or 1/15s) let in more light.
Side Effect: Motion Blur. Fast shutter speeds freeze sports and action. Slow shutter speeds cause moving subjects (and shaky hands) to blur.ISO
Controls the sensor's sensitivity to light. A low ISO (100) is standard for bright daylight. A high ISO (3200, 6400) makes the sensor highly sensitive for dark, indoor environments.
Side Effect: Digital Noise. High ISO introduces grainy, color-splotched artifacts (noise) to the image. It is generally best to keep ISO as low as possible.What is Exposure Value (EV)?
Exposure Value (specifically EV100, which assumes an ISO of 100) is a number representing a specific combination of aperture and shutter speed that yields the same exposure. Any combination of settings that yields the same EV will result in an image of identical brightness.
Where 'N' is the f-stop number, and 't' is time in seconds.
Frequently Asked Questions (FAQ)
What is a "Stop" of light?
Changing your exposure by one "stop" means you are either doubling the amount of light, or cutting the amount of light exactly in half. For instance, moving Shutter Speed from 1/60 to 1/125 cuts the light in half (loss of one stop). To maintain exposure, you must gain a stop somewhere else (e.g., doubling ISO from 100 to 200).
Why are Aperture numbers so strange? (1.4, 2.0, 2.8, 4.0)
Aperture numbers are based on the square root of 2 (approx 1.414). To double the area of a circle (the lens opening), you multiply the diameter by the square root of 2. Therefore, moving from f/2.8 to f/4 halves the light, and from f/4 to f/5.6 halves it again.
Can I use this for Neutral Density (ND) Filters?
Yes! If you put a 10-stop ND filter on your lens, you simply decrease your original shutter speed by 10 full stops. For example, 1/60s minus 10 stops becomes a 15-second exposure.