Equivalent Exposure Calculator

Equivalent exposures keep the overall exposure the same while changing camera settings. Photographic exposure is controlled by three variables: aperture (f-stop), shutter speed, and ISO sensitivity. Changing one variable affects the light captured, and a compensating change in another can produce an identical exposure, without working through the log calculations by hand.

• A reference exposure (aperture, shutter speed, and ISO) and a second, adjusted exposure can be compared side by side. The EV (exposure value) for each is shown, along with the difference between them in stops.
• Finding an equivalent exposure means choosing which parameter absorbs the change: adjusting shutter speed suits aperture priority, adjusting aperture suits shutter priority, and adjusting ISO suits manual mode. The adjusted exposure is then set to match the light captured by the reference.
• Exposure compensation shifts the adjusted exposure by an EV offset, accepting decimals (1.33), fractions (2/3), mixed numbers (1 1/3), and negatives (-2/3).
• A step-by-step EV derivation is available, along with dropdown granularity of 1/3 stop, 1/2 stop, or full stop increments.
• The EV formula is EV = log base 2 of (f-number squared divided by shutter duration in seconds). Light Value normalizes the exposure to ISO 100 for cross-comparison across different sensitivity settings.

Moving from f/5.6 to f/16 is three full stops (f/5.6, f/8, f/11, f/16), and each stop down halves the light reaching the sensor, so the shutter speed must lengthen by a factor of 2 cubed, or 8, to keep the same exposure. Starting from 1/250 second at f/5.6, the equivalent shutter speed at f/16 is 1/250 x 8 = 8/250, or 1/31.25 second, close to the 1/30 second setting available on most cameras.

Photographers at every skill level benefit from understanding equivalent exposures. Whether planning a shoot, troubleshooting exposure in the field, or learning the exposure triangle, the calculator provides instant feedback and educational value.

• Landscape Photography: Determine how to use a smaller aperture like f/16 for maximum depth of field while compensating with a longer shutter speed. A current exposure at f/5.6 finds its equivalent shutter speed at f/16 to maintain identical brightness.
• Sports and Action Photography: Calculate the ISO increase needed when switching from 1/250 second to 1/2000 second to freeze fast motion while keeping the same aperture and exposure level.
• Low Light and Night Photography: Compare a 30-second exposure at ISO 800 with shorter alternatives at higher ISO values to evaluate noise trade-offs while maintaining equivalent exposure.
• Studio Photography: When adjusting strobe power or changing modifiers, exposure compensation shows how many stops of camera adjustment are needed.
• Education and Learning: Students studying the exposure triangle can experiment with combinations and review the step-by-step EV derivation to understand how aperture, shutter speed, and ISO relate mathematically.
• Neutral Density Filter Use: After attaching an ND filter rated at a specific stop reduction, applying that value as negative EV compensation finds the new shutter speed or aperture needed.
• Astrophotography: Compare exposures for star trails versus tracked shots, determining how ISO and shutter speed changes affect total light gathered while staying within star trailing limits.
• Video Production: Find equivalent exposures when locked to specific shutter speeds (such as 1/50 second for 25fps or 1/48 second for 24fps) and aperture or ISO needs to match a target exposure.