Meter your scene
Open the spot meter and tap up to 4 areas you want to control.
Shot Log
Your shots are saved on this device. Export as JSON to back up or transfer to another device.
No shots saved yet. Meter a scene, calculate exposure, and tap "Save Shot to Log" to start building your field notes.
How to Use This Calculator
1. Open the Spot Meter
Tap the spot meter button to use your phone camera as a live light meter. Point it at your scene and the calculator reads the exposure automatically.
2. Tap Up to 4 Areas
Tap the areas you want to control - a shadow, a highlight, skin, sky. Each tap places a numbered pin and detects the brightness zone at that point.
3. Choose How Each Should Look
For each spot, choose the zone you want it to be in your final photo. Dark shadow? Zone III. Bright skin? Zone VI. The calculator finds the best compromise exposure across all your placements.
4. Set Your Camera
Enter your ISO, aperture, camera body, lens, and film stock. The calculator gives you the shutter speed and shows how each metered area will actually render at that exposure.
5. Save to Your Shot Log
Tap "Save Shot to Log" to record the scene, your exposure settings, gear, and film stock. Add notes while the scene is fresh. Export as JSON to keep a permanent record of every shot on a roll.
New to the Zone System?
Read our complete plain-language guide to exposure, metering, and the Zone System - covering everything from how a light meter works to placing and falling in the field, for both film and digital.
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Zone Descriptions
| Zone | Print Value | Subject Description |
|---|---|---|
| 0 | Maximum black | Complete absence of density. No detail, no texture. |
| I | Near black | Effective threshold. Slight tonality but no texture. |
| II | Deep shadow | First suggestion of texture. Deep shadows in a portrait, dark foliage. |
| III | Dark detail | Full texture and detail in shadows. Dark fabric, dark stone, bark. |
| IV | Shadow detail | Well-lit shadow. Dark foliage, landscape shadow, dark skin. |
| V | Middle grey | 18% reflectance grey card. Weathered wood, dark sky, average stone. |
| VI | Light detail | Average Caucasian skin, light stone, clear north sky. |
| VII | Bright detail | Very light skin, bright concrete, snow in side light with full texture. |
| VIII | Near white | Lightest tone with texture. Snow in flat light, white painted wall. |
| IX | Specular | Slight tone without texture. Glare on water, bright clouds. |
| X | Pure white | Maximum paper white. Light sources, specular reflections. |