Frequently asked questions

Android 8.0 (API 26) or later. The app uses modern Camera2 APIs that older Android versions do not support. Almost any phone made after 2018 will work.

Yes. Metering, calculation, logging, gear management, film stock data, and every calculator work entirely offline. The only optional features that use the network are weather, the ephemeris (sun and moon position), and downloading community sensor calibration profiles. You can opt out of all three.

Camera (required, used only while the viewfinder is open, to read light), Location (optional, for the ephemeris and weather), Storage (used when you export shot logs to CSV), and Notifications (optional, used by the bulb timer and reminders). The app never records video, never takes photos, and never sends camera data anywhere.

Out of the box, most phones land within roughly one stop of a Sekonic or comparable handheld. After a one-time calibration against a known reference (a grey card under steady light, or another meter you trust), most users land within one third of a stop, which is the same tolerance as the meter built into a serious film camera. The calibration is saved per device.

Start with reflected center-weighted metering: just point the phone where you want the camera to point and trust the reading. This works for the vast majority of scenes, including most portraits, street, and landscape shots. Move to spot or multi-spot only when the scene has very strong contrast or when you specifically want to control which tone falls where, like with the Zone System.

The Zone System is a way of mapping every tone in a scene onto a 0 to 10 scale, with 5 being middle grey. You read the brightest important highlight and the deepest important shadow, then choose where to place them on the scale, and the exposure follows. It is the most accurate method but takes a few rolls to learn. You do not need it to get good results, but if you want full control, the app has dedicated tools for it.

Sunny 16 is a starting point, not a reading. It assumes a textbook sunny scene with average tonality. If the actual scene is brighter, darker, has lots of snow or shade, or includes haze, Sunny 16 will be off. The meter reads the actual light reflecting off your specific scene, so on negative film, trust the meter and bias for the shadows. On slide film, bias for the highlights.

Backlit portrait: spot-meter the face, not the background. Snow: a reflective meter sees snow as middle grey and tells you to underexpose by about two stops, which would render the snow as muddy grey. Add two stops of exposure compensation, or spot-meter a less reflective part of the scene. The app has a dedicated panic button that walks you through these situations one screen at a time.

Yes. The app supports exposures up to several minutes and includes a built-in bulb timer with haptic and voice countdown so you can keep your eye on the camera. It also calculates reciprocity failure automatically once you select your film stock, which can add anywhere from a few seconds to many minutes to the recommended exposure depending on the stock.

Yes. The app ships with a large database of common cameras, lenses, and film stocks, and you can add your own with custom shutter ranges, aperture ranges, flash sync speeds, and bellows extension factors. Custom gear is saved locally and can be exported.

Add it. The film stock screen lets you create a new stock with custom ISO, latitude, reciprocity curve, push and pull development times, and notes. You can copy from an existing stock and then tweak, which is faster than starting from scratch.

Yes to both, automatically. Tell it which filter is on the lens (red, polarizer, ND, IR, etc.) and it subtracts the filter factor from the recommended exposure. For long exposures, it applies the right reciprocity curve for the loaded film stock. Bellows extension on large format is supported too.

Yes. There is a per-roll setting for how many years past the expiration date the film is, and the app adjusts the recommended exposure based on the standard one-stop-per-decade rule, which you can override per stock if you know your specific film behaves differently.

No. The app has no analytics, no telemetry, no third-party SDKs, no advertising identifiers, and no account system. Everything stays on your phone. The full privacy story is on the privacy page.

Everything is in a local SQLite database on the phone. You can export your shot logs and rolls to CSV at any time from the Logs tab. The CSV opens in any spreadsheet tool and includes a Lightroom-compatible metadata preset.

Yes, unless you exported first. There is no cloud sync to fall back on. This is on purpose, to keep the app local-first, but it means you should export your roll logs occasionally if they matter to you. A two-tap CSV export is built in.

An iOS port is in early development. The Android version is the focus today and has the full feature set. When iOS ships, per-feature pages on this site will note any differences.

Email hello@zonelightmeter.com with what you expected, what happened, your phone model, and Android version. Screenshots help. The developer reads every message personally.

There is no fixed schedule. Updates ship when features are ready, usually every few weeks. Every shipped feature gets a documentation page on this site at the same time, so if it works in your hands it is also documented here.