# ZoneCalc – Zone System Meter — Film Exposure Calculator

> Film exposure calculator for photographers using Ansel Adams' Zone System. (iPhone/iPad app by Juergen Suk.)

- Source: https://appshunter.io/ios/app/zonecalc-zone-system-meter/id6772102746 (this page in markdown: same URL + `.md`)
- Developer: [Juergen Suk](https://appshunter.io/developer/6772102748)
- Category: Photo & Video, Utilities
- Price: Free with in-app purchases
- Rating: 5.00/5 from 2 App Store ratings
- Age rating: 4+
- Requires: iOS 17.6 · 3 MB
- Languages: American English, German (Germany)
- Released: 2026-05-29
- Data updated: 2026-08-09
- Monetization: freemium
- User reviews in markdown: https://appshunter.io/ios/app/zonecalc-zone-system-meter/id6772102746/reviews.md

## What is ZoneCalc?

ZoneCalc — Zone System Calculator

ZoneCalc is a precision tool for large format, medium format and 35 mm photography following Ansel Adams' Zone System. Built for photographers who work with a spot meter, develop their own negatives, and want full control over exposure and tonal placement.

METERING
In Classic mode, enter the shutter speed for the deepest shadow with detail (Zone II) and the brightest highlight with detail (Zone VIII). ZoneCalc returns the shutter speed for Zone V — 18 % middle gray — the exposure you set on the camera.

Multi mode accepts any number of measurement points across the scene. The app auto-assigns each point to a zone; drag pins on the zone strip to express your creative placement intent.

RECIPROCITY
For exposures above one second, the Schwarzschild effect is corrected automatically: t_corr = t_nom ^ p, using the film-specific exponent. The corrected camera time appears directly in the result card. The shutter speed list extends to 30 minutes.

Films with reciprocity data: Ilford HP5+, FP4+, Delta 100/400, Kodak Tri-X, T-Max 100/400, Kodak Portra 160/400/800, Leica Monopan.

N-RATING & DEVELOPMENT
ZoneCalc compares the scene's dynamic range against the film's usable latitude and proposes a development adjustment — N−2 through N+2. For each film, concrete times are shown for common developers: D-76, Rodinal, HC-110, XTOL, ID-11, T-Max Dev — with dilutions per Massive Dev Chart and manufacturer recommendations.

HISTORY & EXPORT
Every calculation can be saved with a note and the chosen developer; two entries can be compared side by side. The complete result — shutter speed, reciprocity, N-rating and development times — exports as an image for the darkroom or for sharing via AirDrop, message or mail.

DESIGN
The interface follows the visual language of classic Leica instruments: monospaced typography, warm amber accent, hard edges instead of rounded corners. Fully localized in English and German, all-dark throughout — optimized for darkroom and field use.

ZONECALC PRO
Classic two-point metering with Zone V calculation and the zone strip are free. The one-time Pro upgrade unlocks:
— Multi-point metering with interactive zone assignment
— Reciprocity correction and N-rating
— Development recommendations with times per developer
— Save, compare and image export

One app, no subscriptions, no data collection. All calculations run locally on device.

## Key features

- Zone System exposure calculation
- Multi-point metering
- Reciprocity correction
- Development adjustment recommendations
- Film-specific development times
- Calculation history and export

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| ZoneCalc Pro | $3.99 | one-time |



## Frequently asked questions about ZoneCalc

### What is ZoneCalc used for?

ZoneCalc is a precision tool for photographers following Ansel Adams' Zone System. It helps calculate exposure and tonal placement for film photography, offering features like metering, reciprocity correction, and development adjustments.

### Does ZoneCalc have ads?

No, ZoneCalc does not contain advertisements. The app is designed to be ad-free for an uninterrupted user experience.

### What is the price of ZoneCalc?

ZoneCalc is free to download and use. A one-time Pro upgrade is available to unlock additional features, but there are no subscriptions.

### What are the Pro features in ZoneCalc?

The Pro upgrade unlocks multi-point metering with interactive zone assignment, reciprocity correction, N-rating, development recommendations with times, and the ability to save, compare, and export calculations as images.

### What film types does ZoneCalc support for reciprocity data?

ZoneCalc supports reciprocity data for films such as Ilford HP5+, FP4+, Delta 100/400, Kodak Tri-X, T-Max 100/400, Kodak Portra 160/400/800, and Leica Monopan.

### How does ZoneCalc handle reciprocity correction?

For exposures over one second, ZoneCalc automatically corrects for the Schwarzschild effect using a film-specific exponent. The corrected camera time is displayed directly in the result card, with shutter speeds extending up to 30 minutes.

### What is the update frequency for ZoneCalc?

ZoneCalc was last updated on August 3, 2026, indicating active development. The current version is 1.2.

### Is ZoneCalc available on Android devices?

Currently, ZoneCalc is only supported on iPhone devices. It is not available for Android smartphones or tablets.

## Version history (last 5 releases)

### 1.2 — 2026-08-03

You can now enter custom aperture values for pinhole work. The aperture picker has a free-entry field, so f-numbers beyond f/32, such as f/138, feed straight into the Zone System calculation.

### 1.1 — 2026-07-15

Custom Development Times (Pro)

You can now add your own tested development times – per film and
developer, for N−2 through N+2. They appear with a CUSTOM marker
right next to the built-in database on the development time card,
and can be managed centrally in Settings.

• Your own times per film, developer, dilution and temperature
• Overview, edit and delete in Settings
• Seamlessly integrated into the existing N-rating recommendation

Also: a clearer Pro overview in Help – see at a glance what Pro unlocks.

Thanks for the community feedback – more improvements to come.

### 1.0.2 — 2026-06-30

New film stocks with complete reciprocity and development data:

- Fujifilm Acros 100 II – threshold logic applied: 
  no correction up to 120 s, Schwarzschild p = 1.15 beyond
- Fomapan 100 Classic / 200 Creative / 400 Action
- Ilford Pan F+ 50
- Ilford Ortho+ 80

Development times for all new films:
Rodinal, D-76, HC-110 – N-2 through N+2 at 20 °C

Bug fix: N+2 development times were missing for select films – now complete across all stocks.

### 1.0.1 — 2026-06-12

1/3-Stop Aperture Steps:
The aperture picker now moves in 1/3-stop increments — f/2.8, f/3.2, f/3.5, f/4, and so on. If your lens has 1/3-stop click stops (most modern lenses do, as do many classics), your input now matches your actual glass.

Free ISO/EI Entry + 1/3-Stop ISO Steps:
The ISO picker has been replaced with a free-entry field stepping in 1/3 stops. Values like EI 40, 80, 160, and 250 are now directly accessible. Rate HP5+ at EI 320 or shoot Rollei RPX 25 at box speed — no more forced rounding.

Performance fix: resolved a lag issue on iPhone 12 Pro.

### 1.0 — 2026-05-29

No release notes.

## Apps similar to ZoneCalc

| App | Rating | Price | Category |
| --- | --- | --- | --- |
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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-09.*