露出トライアングル計算機

共有リンク

はじめに

Exposure Triangle Calculator — Calculate exposure value (EV) from aperture, shutter speed, and ISO. Enter Aperture (f-number), Shutter Speed (seconds), ISO to get an instant, accurate result.

計算式

EV at ISO 100 = log2(N² / t), where N is the f-number (aperture) and t is shutter speed in seconds. EV at a given ISO = EV100 − log2(ISO/100).

ステップごとの説明

Enter the Aperture (f-number).
Enter the Shutter Speed (seconds).
Enter the ISO.
Click Calculate to see your result instantly.

実例

Example: With Aperture (f-number) = 8, Shutter Speed (seconds) = 0.008 s, ISO = 100, the Exposure Triangle Calculator gives Ev100: 12.9658, Ev: 12.9658.

よくある質問

What does a higher EV number mean?

A higher exposure value means less light is needed — it corresponds to a brighter scene or a combination of settings that lets in less light (smaller aperture, faster shutter, lower ISO).

Why does ISO subtract from EV100 instead of add?

Raising ISO amplifies the sensor's sensitivity, which is equivalent to needing less light — so it lowers the effective exposure value required, hence the subtraction.

What inputs does the Exposure Triangle Calculator need?

You'll need to provide: Aperture (f-number), Shutter Speed (seconds), ISO. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.

How accurate is the Exposure Triangle Calculator?

The Exposure Triangle Calculator applies the formula exactly as calculated — EV at ISO 100 = log2(N² / t), where N is the f-number (aperture) and t is shutter speed in seconds. EV at a given ISO = EV100 − log2(ISO/100). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.

Is the Exposure Triangle Calculator free to use?

Yes, the Exposure Triangle Calculator is completely free, requires no signup, and runs instantly in your browser.