Stopwise
曝光轉盤 · Exposure dial for manual cameras
Stopwise 不是測光儀，是曝光換算表。它不使用相機、也不讀取光線感測器。你輸入已知的條件（EV 值，或現有的光圈／快門／ISO 組合），它換算出等效的曝光參數組合。完全離線。
Stopwise is not a light meter — it is an exposure calculator. It does not use your camera or any light sensor. You enter what you already know (an EV value, or an existing aperture / shutter / ISO combination) and it works out the equivalent settings. Fully offline.
怎麼用 · How it works
三個轉盤分別是光圈、快門、ISO。每一列右邊有一個鎖頭。
Three dials: aperture, shutter, ISO. Each row has a lock on the right.
| 鎖定數量 | 行為 · Behaviour |
|---|---|
| 鎖 1 項 One locked |
撥動任一開啟的轉盤，由另一個開啟的轉盤補償，EV 不變。這是等效曝光換算。 Turn either open dial; the other compensates and the EV stays the same. |
| 鎖 2 項 Two locked |
只剩一個轉盤可撥，撥動它會直接改變 EV。用來從已知的組合反推 EV。 Only one dial is left; turning it changes the EV. Use this to derive EV from a known combination. |
鎖定數量必須是 1 或 2。一項都不鎖時，撥動一個轉盤會有兩個候選可以補償，誰會動無從預期，所以不允許。
You must keep one or two locked. With none locked there would be two possible compensators and no way to predict which one moves, so it is not allowed.
免費版與專業版 · Free and Pro
| 免費版 · Free | 專業版 · Pro | |
|---|---|---|
| 光圈 · Aperture | f1.4 – f22 | f0.8 – f56 |
| 快門 · Shutter | 120" – 1/4000 | 300" – 1/8000 |
| ISO | 100 – 1000 | 32 – 102400 |
| 級距 · Step size | 1/3 級 · 1/3 stop | 1/2 或 1/3 級 |
| 場景 · Scenes | — | 12 個內建 + 自訂 20 組 |
專業版是一次購買、永久使用，沒有訂閱、沒有廣告。換算核心兩個版本完全相同。
Pro is a one-time purchase. No subscription, no ads. The calculation engine is identical in both versions.
常見問題 · FAQ
算出來的值跟我的相機刻度不完全一樣？
那是正常的。f/11、1/125 這類是攝影界的慣用標籤，不是精確值 —— f/11 的精確值其實是 11.3137，1/125 其實是 1/128。Stopwise 內部一律用精確值計算，只在顯示時換成你熟悉的標籤。這也是為什麼它算得比心算準。
Why don't the numbers exactly match my camera's markings? They aren't meant to. Labels like f/11 and 1/125 are conventional approximations — the exact values are 11.3137 and 1/128. Stopwise always calculates with exact values and only rounds for display.
為什麼不用手機相機測光？
因為手機相機的測光準確度不可控 —— 鏡頭、感光元件、系統版本都會影響讀數，而且無法校正。Stopwise 選擇只做數學：只要公式和級距序列正確，結果就是正確的，不依賴任何硬體。
Why no camera metering? Phone camera metering varies by lens, sensor and OS version, and cannot be reliably calibrated. Stopwise does only the maths, which is exact and hardware-independent.
換手機之後專業版不見了？
打開設定 → 恢復購買。請確認登入的是當初購買時使用的 App Store 帳號。
Lost Pro after changing device? Open Settings → Restore Purchases, signed in with the same App Store account used for the original purchase.
免費版的 ISO 為什麼只到 1000？
ISO 100–1000 涵蓋了大多數常見底片與日常拍攝。更低（如 ISO 50 的正片）與更高（數位高感光）的範圍屬於專業版。
Why is free ISO limited to 1000? ISO 100–1000 covers most common films and everyday shooting. Slower films and high-ISO digital ranges are part of Pro.
聯絡我們 · Contact
有問題、發現錯誤、或想建議功能，歡迎來信：
Questions, bug reports and feature requests are welcome:
回報換算結果有誤時，請附上光圈、快門、ISO、級距設定與你預期的數值，這樣最容易重現。
When reporting a calculation problem, please include the aperture, shutter, ISO and step-size setting, plus the value you expected.