Initial Release

This commit is contained in:
2026-04-08 15:49:54 +02:00
commit cb38916131
3 changed files with 438 additions and 0 deletions

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app.css Normal file
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:root {
--bg: #0f1220;
--panel: #171a2b;
--panel-2: #1f2438;
--text: #eef2ff;
--muted: #b8c0e0;
--accent: #7aa2ff;
--ok: #67e8a5;
--error: #ff8b8b;
--border: #2e3552;
}
* {
box-sizing: border-box;
}
body {
margin: 0;
font-family:
system-ui,
-apple-system,
Segoe UI,
Roboto,
Helvetica,
Arial,
sans-serif;
background: var(--bg);
color: var(--text);
min-height: 100vh;
}
.wrap {
max-width: 1000px;
margin: 0 auto;
padding: 28px 16px 48px;
}
h1 {
margin: 0 0 8px;
font-size: 1.7rem;
letter-spacing: 0.2px;
}
.subtitle {
margin: 0 0 24px;
color: var(--muted);
font-size: 0.98rem;
line-height: 1.45;
}
.grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 16px;
}
@media (max-width: 900px) {
.grid {
grid-template-columns: 1fr;
}
}
.card {
background: var(--panel);
border: 1px solid var(--border);
border-radius: 14px;
padding: 16px;
}
.card h2 {
margin: 0 0 14px;
font-size: 1.05rem;
color: #dbe4ff;
}
.field {
margin-bottom: 12px;
}
label {
display: block;
margin-bottom: 6px;
font-size: 0.9rem;
color: var(--muted);
}
input {
width: 100%;
border: 1px solid var(--border);
background: #0f1324;
color: var(--text);
border-radius: 10px;
padding: 10px 12px;
font-size: 0.98rem;
outline: none;
}
input:focus {
border-color: var(--accent);
box-shadow: 0 0 0 3px rgba(122, 162, 255, 0.18);
}
.hint {
font-size: 0.82rem;
color: var(--muted);
margin-top: 4px;
}
.actions {
margin-top: 6px;
display: flex;
gap: 10px;
flex-wrap: wrap;
}
button {
border: 1px solid var(--border);
background: #243051;
color: var(--text);
border-radius: 10px;
padding: 10px 14px;
cursor: pointer;
font-weight: 600;
}
button:hover {
filter: brightness(1.08);
}
button:active {
transform: translateY(1px);
}
.result {
margin-top: 18px;
background: #10182e;
border: 1px solid var(--border);
border-radius: 12px;
padding: 14px;
line-height: 1.45;
}
.ok {
color: var(--ok);
font-weight: 700;
}
.error {
color: var(--error);
font-weight: 700;
}
.mono {
font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
background: rgba(255, 255, 255, 0.06);
padding: 2px 6px;
border-radius: 6px;
}
.formula {
margin-top: 16px;
color: var(--muted);
font-size: 0.88rem;
line-height: 1.5;
}
.formula code {
color: #d6e2ff;
}
.small {
font-size: 0.86rem;
color: var(--muted);
margin-top: 10px;
}

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const isoAEl = document.getElementById("isoA");
const fAEl = document.getElementById("fA");
const tAEl = document.getElementById("tA");
const isoBEl = document.getElementById("isoB");
const fBEl = document.getElementById("fB");
const tBEl = document.getElementById("tB");
const resultEl = document.getElementById("result");
document.getElementById("calcBtn").addEventListener("click", calculate);
document.getElementById("resetBtn").addEventListener("click", reset);
document.addEventListener("keydown", (e) => {
if (e.key === "Enter") calculate();
});
function parseShutter(value) {
const raw = String(value ?? "").trim();
if (!raw) return NaN;
if (raw.includes("/")) {
const parts = raw.split("/");
if (parts.length !== 2) return NaN;
const num = parseFloat(parts[0]);
const den = parseFloat(parts[1]);
if (!isFinite(num) || !isFinite(den) || den === 0) return NaN;
return num / den;
}
const v = parseFloat(raw);
if (!isFinite(v)) return NaN;
return v;
}
function parsePositiveOrEmpty(value, parser = parseFloat) {
const raw = String(value ?? "").trim();
if (raw === "") return { empty: true, value: null };
const parsed = parser(raw);
if (!isFinite(parsed) || parsed <= 0) return { empty: false, value: NaN };
return { empty: false, value: parsed };
}
function prettyShutter(seconds) {
if (!(seconds > 0) || !isFinite(seconds)) return "Invalid";
// exact decimal seconds (up to 8 decimals, trimmed)
const exactSeconds = seconds.toFixed(8).replace(/0+$/, "").replace(/\.$/, "");
if (seconds < 1) {
// exact reciprocal (not snapped to common shutter values)
const reciprocal = 1 / seconds;
const reciprocalStr = reciprocal
.toFixed(6)
.replace(/0+$/, "")
.replace(/\.$/, "");
return `1/${reciprocalStr} s (${exactSeconds} s)`;
}
return `${exactSeconds} s`;
}
function formatAperture(n) {
if (!(n > 0) || !isFinite(n)) return "Invalid";
return `f/${n.toFixed(2).replace(/0+$/, "").replace(/\.$/, "")}`;
}
function formatISO(iso) {
if (!(iso > 0) || !isFinite(iso)) return "Invalid";
return `ISO ${Math.round(iso)}`;
}
function calculate() {
// Reference (must all be present)
const isoA = parseFloat(isoAEl.value);
const fA = parseFloat(fAEl.value);
const tA = parseShutter(tAEl.value);
if (
!(isoA > 0) ||
!(fA > 0) ||
!(tA > 0) ||
!isFinite(isoA) ||
!isFinite(fA) ||
!isFinite(tA)
) {
resultEl.innerHTML = `<span class="error">Camera A must have valid positive ISO, f-stop, and shutter speed.</span>`;
return;
}
// Camera B: exactly one missing
const isoBParsed = parsePositiveOrEmpty(isoBEl.value, parseFloat);
const fBParsed = parsePositiveOrEmpty(fBEl.value, parseFloat);
const tBParsed = parsePositiveOrEmpty(tBEl.value, parseShutter);
const fields = [
{ key: "iso", ...isoBParsed },
{ key: "f", ...fBParsed },
{ key: "t", ...tBParsed },
];
const emptyFields = fields.filter((f) => f.empty);
if (emptyFields.length !== 1) {
resultEl.innerHTML = `<span class="error">For Camera B, leave exactly one field empty (the one to calculate).</span>`;
return;
}
if (fields.some((f) => !f.empty && (!isFinite(f.value) || f.value <= 0))) {
resultEl.innerHTML = `<span class="error">Camera B has invalid values. Use positive numbers, and shutter like 1/250 or 0.004.</span>`;
return;
}
const missing = emptyFields[0].key;
let isoB = isoBParsed.value;
let fB = fBParsed.value;
let tB = tBParsed.value;
// From:
// tB = tA * (fB^2 / fA^2) * (isoA / isoB)
// Rearranged for each missing variable:
if (missing === "t") {
tB = tA * ((fB * fB) / (fA * fA)) * (isoA / isoB);
if (!(tB > 0) || !isFinite(tB)) {
resultEl.innerHTML = `<span class="error">Could not compute shutter speed from given values.</span>`;
return;
}
tBEl.value = tB.toPrecision(6);
resultEl.innerHTML = `
<div class="ok">Calculated shutter speed for Camera B: <span class="mono">${prettyShutter(tB)}</span></div>
<div style="margin-top:8px;">B now: <span class="mono">${formatISO(isoB)}, ${formatAperture(fB)}, ${prettyShutter(tB)}</span></div>
`;
return;
}
if (missing === "iso") {
// isoB = isoA * tA * fB^2 / ( tB * fA^2 )
isoB = (isoA * tA * (fB * fB)) / (tB * (fA * fA));
if (!(isoB > 0) || !isFinite(isoB)) {
resultEl.innerHTML = `<span class="error">Could not compute ISO from given values.</span>`;
return;
}
isoBEl.value = Math.round(isoB).toString();
resultEl.innerHTML = `
<div class="ok">Calculated ISO for Camera B: <span class="mono">${formatISO(isoB)}</span></div>
<div style="margin-top:8px;">B now: <span class="mono">${formatISO(isoB)}, ${formatAperture(fB)}, ${prettyShutter(tB)}</span></div>
`;
return;
}
if (missing === "f") {
// fB^2 = (tB * fA^2 * isoB) / (tA * isoA)
// fB = sqrt(...)
const inside = (tB * (fA * fA) * isoB) / (tA * isoA);
fB = Math.sqrt(inside);
if (!(fB > 0) || !isFinite(fB)) {
resultEl.innerHTML = `<span class="error">Could not compute aperture from given values.</span>`;
return;
}
fBEl.value = fB.toFixed(2);
resultEl.innerHTML = `
<div class="ok">Calculated aperture for Camera B: <span class="mono">${formatAperture(fB)}</span></div>
<div style="margin-top:8px;">B now: <span class="mono">${formatISO(isoB)}, ${formatAperture(fB)}, ${prettyShutter(tB)}</span></div>
`;
}
}
function reset() {
isoAEl.value = "100";
fAEl.value = "2.0";
tAEl.value = "1/1000";
isoBEl.value = "";
fBEl.value = "";
tBEl.value = "";
resultEl.textContent = "Result will appear here.";
}

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<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Exposure Match Calculator (ISO / Aperture / Shutter)</title>
<link rel="stylesheet" href="app.css">
</head>
<body>
<div class="wrap">
<h1>Exposure Match Calculator</h1>
<p class="subtitle">
Enter a full reference exposure (Camera A). For Camera B, fill
exactly <strong>two</strong> fields and leave
<strong>one empty</strong>. The empty field is calculated for
equal exposure.
</p>
<div class="grid">
<section class="card">
<h2>Camera A (Reference: all required)</h2>
<div class="field">
<label for="isoA">ISO</label>
<input id="isoA" type="number" min="1" step="1" value="100" />
</div>
<div class="field">
<label for="fA">F-Stop (aperture N)</label>
<input id="fA" type="number" min="0.1" step="0.1" value="2.0" />
</div>
<div class="field">
<label for="tA">Shutter Speed</label>
<input id="tA" type="text" value="1/1000" />
<div class="hint">Examples: 1/250, 0.004, 2</div>
</div>
</section>
<section class="card">
<h2>Camera B (Target: leave one empty)</h2>
<div class="field">
<label for="isoB">ISO (leave empty to calculate ISO)</label>
<input id="isoB" type="text" />
</div>
<div class="field">
<label for="fB">F-Stop (leave empty to calculate aperture)</label>
<input id="fB" type="text" />
</div>
<div class="field">
<label for="tB">Shutter (leave empty to calculate shutter)</label>
<input id="tB" type="text" />
<div class="hint">Examples: 1/125, 0.008, 1.5</div>
</div>
<div class="actions">
<button id="calcBtn">Calculate Missing Value</button>
<button id="resetBtn" type="button">Reset</button>
</div>
<div class="result" id="result">
Result will appear here.
</div>
</section>
</div>
<div class="formula">
Exposure equivalence model (same scene brightness):<br />
<code>(N² / t) × (100 / ISO)</code> is constant, or
equivalently<br />
<code>t₂ = t₁ × (N₂² / N₁²) × (ISO₁ / ISO₂)</code>
</div>
<div class="small">
Note: This is a technical equivalence calculator (ignores
artistic/real-world differences like sensor noise, transmission
losses, etc.).
</div>
</div>
<script src="app.js"></script>
</body>
</html>