Z vs EVen

Expose for the shadows, develop for the highlights. Z-Stop is an iPhone spot meter true to this Zone System principle. Shoot black-and-white film with the Zone System, no external meter needed. [ Sound familiar? ] - Your mechanical or MF camera has no meter, so you carry a separate spot meter. - You meter with a DSLR, then copy the values to your film camera. - You metered a shadow, shot at that value, and the picture came out too bright. - By the time you develop, you can't remember where you metered. Meter one shadow with your iPhone, and Z-Stop shows the shutter speed and aperture that place it on Zone 3, in ½-stop steps. With Pro, one tap on "Save" keeps the scene as a record image. [ The Zone System ] Set out by Ansel Adams and Fred Archer around 1940, it divides tones from black (Zone 0) to white (Zone 10) into 11 steps. One zone is one stop. Zone 3 is the darkest shadow with full texture: dark clothing, bark in shade. Zone 5 is middle gray: an 18% gray card. The rule: expose for the shadows, develop for the highlights. [ A meter only tells you Zone 5 ] Any reflected-light meter gives the exposure that renders the metered spot as middle gray (Zone 5). Meter a shadow and shoot at that value, and the shadow turns gray. To place it on Zone 3, give 2 stops less, measured on that one spot. That is why you need spot metering. [ What Z-Stop does ] * Spot metering on your iPhone - Measures only inside a small circle on the screen. * Checks the shadow - A green "Z3 OK" if the spot is even enough to use, a red "Re-meter" if pattern or edges are mixed in. * Finds a spot for you - "Find Zone 3" marks usable spots. With no Zone 3 it looks for Zone 4, and with neither it says "Don't shoot." * Does the math - Takes off 2 stops and converts to your body's shutter steps and your lens's aperture range. - If a step can't be set, the warning tells you what to change (e.g. Open the aperture · Remove the ND). * Five steps for half-stop differences - From the reading down to -2 stops in ½ stops. - Full-stop shutters: missing steps are grayed out, and "By aperture" splits them by aperture. * Keeps a record (Pro) - The record image keeps the scene, readings, shutter and aperture in the same layout as the metering screen. * Previews black-and-white tones [ How to use ] 1. Tap a dark spot, or tap "Find Zone 3" at the bottom left of the camera view and tap a circle. The circle becomes the reference right away. For a spot you metered yourself, tap its green "Z3 OK" box. 2. Five steps appear (+1 to -1 stop with a Zone 4 reference). 3. -2 stops is the theory; the right step shifts by about half a stop with film, EI and development. For your first roll, shoot -2 · -1.5 · -1 stops. After developing, the frame where the Zone 3 shadows show their shapes is your chosen frame. 4. With Pro, tap "Save" at the bottom left of the camera view. The record image goes to the "Z-Stop" album in Photos. [ Free and Pro ] Free: metering, Find Zone 3, the five steps, By shutter, By aperture, B&W preview and all settings. Pro (yearly subscription) unlocks saving record images. [ Also ] Setup: body, EI, aperture, lens (max and min aperture), ND, EV calibration. Find your body in "How to choose a body". Privacy: no network use except Apple's subscription check, no ads or analytics, video stays on your iPhone. Terms of Use: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ * A reflected-light meter based on the iPhone's main camera. Development (highlights) is up to you. * Before important shoots you can't redo (weddings, trips, paid work), always test first with a roll or two to set your EI and chosen frame.

Read the light. Focus on the photograph. EVen is a reflected-light meter that uses your device’s camera exposure information to calculate ISO, aperture, and shutter speed. Continuous metering, priority modes, and exposure compensation come together on one clear screen. • Continuous or tap-to-meter Tap the center box to switch between LIVE and TAP. The label at the top shows the current mode. Continuous metering starts on launch and resume. In tap mode, tap the bottom meter button for a fresh reading that stays until your next tap. Your choice is remembered, and the screen stays awake while you use the app. • Pick up where you left off Your last A/S/M mode, ISO, aperture, shutter speed, and exposure compensation are saved automatically on your device. Reopen the app with your chosen values intact. Only the automatic value updates with the light: shutter speed in A mode, aperture in S mode. No need to set up again. • Choose your priority In A mode, set ISO and aperture to calculate shutter speed. In S mode, set ISO and shutter speed to calculate aperture. In M mode, adjust all three values and see the difference from your target exposure. • Make exposure your own Adjust from −3 to +3 EV in ⅓-stop steps. Positive compensation recommends a brighter exposure; negative compensation recommends a darker one. Apply compensation to a measured result and reset to 0 EV with one tap. • Familiar stop increments Choose full, half, or third stops independently for aperture and shutter speed. Your choice applies to the dial and calculated recommendations. • Camera data, designed for accuracy Exposure values are calculated from the ISO, aperture, and shutter-speed metadata reported by your camera. • Center spot or center weighted Center spot is the default. Choose center-weighted metering in Settings. On supported devices with iOS 26 or later, the spot region matches the inside of the center box. Unsupported regions fall back to center-weighted or automatic metering, with the applied method shown on screen. • A layout that fits your screen Wide and landscape windows place the preview and controls side by side. Portrait screens fit the preview and controls without scrolling. Very large accessibility text or unusually short windows can still scroll. • Guided camera calibration Follow a simple guide to compare with a reference camera or meter. Device calibration is stored locally and kept separate from creative exposure compensation. • A quieter interface Appearance and language follow your system by default. You can also choose light or dark mode and select Korean or English. Target settings span ISO 25–25600, f/1–64, and 30 seconds–1/8000 second. • Private by design No account, ads, or in-app purchases. Camera frames and meter readings are never saved or uploaded. A physical iPhone or iPad with a rear camera and camera permission is required. The displayed exposure settings are intended for your camera or film; they do not change the phone’s physical aperture. Reflected-light readings vary with subject reflectance, backlighting, very low light, and device characteristics. Compare and calibrate against a reference meter before important shoots.