Exposure
Exposure Value Calculator
EV100 = log2(N²/t).
Enter the exposure values
For Exposure Value, keep units and the camera, meter, frame, or lighting reference attached to every entry.
The exposure result will appear here with supporting checks.
The exposure question answered by Exposure Value Calculator
EV100 = log2(N²/t).
The calculator reports ev100 from Aperture f-number, Shutter time. Treat Aperture f-number, Shutter time, and ev100 as one Exposure Value case. Mixing Aperture f-number from one frame with Shutter time from another would answer a different question.
Use it when comparing manual settings, meter readings, or lighting continuity.
Recording the inputs behind ev100
Record Aperture f-number and Shutter time with their displayed units. For Exposure Value, retain any ISO convention, sensor or lens reference, meter constant, pixel basis, and clock date that gives Shutter time its intended meaning.
Identify whether Aperture f-number came from EXIF, a handheld meter, an equipment specification, or a field measurement; those sources may use different conventions. Note the source beside the saved result.
How Exposure Value Calculator calculates its result
EV100 = log2(N²/t).
Exposure Value Calculator evaluates the entered values at full precision; rounding is reserved for the displayed ev100. Predict the direction of ev100 before calculating: changing Aperture f-number alone should produce a physically explainable response.
Checking aperture f-number with the starting values
For Exposure Value, run the published values unchanged and save ev100. The supporting values beneath ev100 expose the ratio, stop change, timing quantity, or sensor measurement used to check this particular model.
Then change only Shutter time. Return Shutter time to its published value afterward and confirm the original ev100 appears again. Changing only Shutter time isolates its effect; moving every Exposure Value input together would conceal which assumption caused the difference.
Where Exposure Value stops
Scene brightness is not inferred; this reports the exposure value represented by the two camera settings.
EV100 alone cannot decide whether the resulting blur, highlight placement, noise, optical behavior, or timing serves the intended photograph.
Reading ev100 in stops and ratios
When interpreting ev100, remember that one stop doubles light, time, or ISO but changes an f-number by the square root of two. The labels in Exposure Value Calculator determine which version belongs in the equation.
When Aperture f-number changes, state whether ev100 rises or falls and whether that direction adds or removes recorded exposure. That direction check prevents a sign error when the displayed scale for Aperture f-number runs opposite to the underlying physical opening, time, or margin.
Verifying ev100 against the camera or meter
Compare ev100 with the camera display, raw histogram, meter, stopwatch, lighting test, or known reciprocal-rule case that applies. If the independent check disagrees with ev100, inspect Aperture f-number, Shutter time, and their units instead of averaging incompatible answers.
The Equivalent Exposure Calculator provides a nearby exposure check when the next question changes. Carry Aperture f-number into the neighboring calculation only when it still refers to the same frame, light, camera, and exposure plan.
Translating ev100 to available settings
EV100 may fall between the full-, half-, or third-stop choices available on the camera or lens used for Exposure Value. Keep the unrounded ev100 for comparison, then choose the available setting that protects the photographic priority.
If Shutter time reaches a flash-sync, aperture, ISO, shutter, stabilization, or motion limit, move the remaining stop change to an available control and rerun Exposure Value.
Saving a reproducible Exposure Value case
Save Aperture f-number, Shutter time, ev100, units, date, camera or meter reference, and the calculator name. Mark measurements separately from assumptions.
For Exposure Value, when the light, framing, subject, or equipment changes, keep the earlier ev100 as a labeled baseline. A later Exposure Value version should differ because Aperture f-number, Shutter time, or another recorded input changed—not because an undocumented correction was applied.
Measurement boundary for Exposure Value
Define exactly where Aperture f-number begins and ends and what the entered Shutter time includes. For Exposure Value, distinguish a value measured at the subject, derived from reflected light, read from the camera, or taken from an equipment specification.
List deliberate exclusions beside ev100. An omitted stabilization allowance, motion pattern, transmission loss, clipping rule, changing light level, or calibration of Shutter time can alter how this output should be interpreted.
For Exposure Value, apply one boundary to both the practical test and the saved Exposure Value record. If Aperture f-number already contains a filter, crop, calibration, safety, or correction allowance, do not add that same adjustment a second time when reporting ev100.
Questions about exposure value calculator
What does Exposure Value Calculator return?
It returns ev100 from Aperture f-number, Shutter time using this relationship: EV100 = log2(N²/t).
Which entry should I verify first?
Verify Aperture f-number and its unit, then confirm that every other value describes the same exposure setup.
What is the main limitation of this result?
Scene brightness is not inferred; this reports the exposure value represented by the two camera settings.