Exposure Calculator

The exposure triangle consists of three camera settings that control how much light reaches your sensor: Aperture (f-stop) controls the lens opening size—lower f-numbers (f/1.8) let in more light but reduce depth of field; Shutter speed controls how long the sensor is exposed—1/1000s freezes motion while 1s creates blur; ISO controls sensor sensitivity—higher ISO brightens the image but adds noise. These three settings are interdependent: if you change one, you must adjust another to maintain the same exposure. For example, if you want a faster shutter speed, you need a wider aperture or higher ISO.

A Neutral Density (ND) filter is a darkened glass that reduces the amount of light entering your lens without affecting colors. ND filters are measured in 'stops' of light reduction: ND2 = 1 stop, ND4 = 2 stops, ND8 = 3 stops, ND1000 = 10 stops. Use ND filters when: you want slow shutter speeds in bright daylight (silky waterfalls, motion blur), you need a wide aperture for shallow depth of field in sunlight, or for long exposures during daytime (light trails, removing moving people). A 10-stop ND filter can turn a 1/1000s exposure into a 1-second exposure.

Exposure Value (EV) is a single number representing a combination of aperture and shutter speed at ISO 100. The formula is: EV = log₂(N²/t), where N is the f-number and t is the shutter time in seconds. EV 0 corresponds to f/1 at 1 second. Each +1 EV halves the light (one stop darker), each -1 EV doubles the light (one stop brighter). Typical scenes: EV 15 = bright sunny day, EV 12 = overcast, EV 8 = bright indoor, EV 3 = dimly lit room, EV -4 = starlight. EV helps communicate lighting conditions and exposure settings in a standardized way.

Equivalent exposures maintain the same total light by trading off aperture, shutter speed, and ISO. Each full stop change doubles or halves the light. Examples starting from f/8, 1/125s, ISO 100: To freeze action (faster shutter): f/5.6, 1/250s, ISO 100 (opened aperture 1 stop). To blur background (wider aperture): f/4, 1/500s, ISO 100 (increased shutter 2 stops to compensate). To shoot in low light: f/8, 1/125s, ISO 400 (raised ISO 2 stops instead). The key is ensuring total light change equals zero: if you lose 2 stops on aperture, gain 2 stops via shutter or ISO.

Common exposure mistakes: Using Auto ISO without limits—set a maximum (e.g., ISO 6400) to prevent excessive noise. Ignoring the sunny 16 rule—in bright sun, use f/16 with shutter speed = 1/ISO (e.g., f/16, 1/100s at ISO 100). Forgetting exposure compensation when using filters—always calculate the new shutter speed (double it for each filter stop). Trusting the LCD preview—check the histogram for accurate exposure; the middle should have data without clipping highlights (right edge) or shadows (left edge). Over-relying on automatic modes—learn manual mode to handle tricky lighting like backlit subjects or snow scenes.