Exposure Match Calculator

A tiny static web app that calculates equivalent camera exposure settings between a reference camera (A) and a target camera (B).

How it works

The app uses exposure equivalence:

(N² / t) × (100 / ISO) = constant

Equivalent rearranged form:

t₂ = t₁ × (N₂² / N₁²) × (ISO₁ / ISO₂)

Where:

• N = f-number (aperture)
• t = shutter time in seconds
• ISO = sensor sensitivity value

Usage

1. Open the app in your browser.
2. Fill all values for Camera A (reference).
3. In Camera B (target), enter exactly two values and leave one empty.
4. Click Calculate Missing Value.
5. The app computes the missing target value for equal exposure.

Run locally

No build tools required.

• Clone the repository.
• Either:

  • Open index.html in your browser.

  • Or start a http server inside the repo directory, e.g. with:

      python -m http.server
    

    and navigate to localhost:8000 in your browser.

License (GPLv3)

This project is licensed under the GNU General Public License v3.0 (GPL-3.0).
You are free to use, modify, and redistribute this software under the terms of that license.
If you distribute modified versions, you must also provide the source code and keep it under GPLv3.

See the LICENSE file for the full license text.

Notes

• Shutter input supports values like 1/250, 0.004, or 2.
• Calculator is for technical equivalence; real-world image differences (noise, lens transmission, dynamic range) still apply.