Focal Length Calculator vs ZoneCalc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Focal Length Calculator
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35mm equivalent Focal Length Multiplier Calculator This calculator allows you to calculate the 35mm equivalent Focal Length for digital camera at specific sensor size. Focal Length and Angle of view. The focal length of the lens is the distance between the lens and the image sensor when the subject is in focus, usually stated in millimeters (e.g., 28 mm, 50 mm, or 100 mm). In the case of zoom lenses, both the minimum and maximum focal lengths are stated, for example 18–55 mm. The shortest focal length, or "ultra wide-angle"lenses, range from 14mm to 20mm, and are followed by "wide-angle" lenses from 24mm to 35mm, and then "standard" lenses from 45 to 70mm, which are similar to the field of view of the human eye. Angle of view. In photography, angle of view (AOV) describes the angular extent of a given scene that is imaged by a camera. It is important to distinguish the angle of view from the angle of coverage, which describes the angle range that a lens can image. Certain digital cameras require a focal length multiplier in order to ensure the photographer is getting the angle of view they are expecting. This only became a factor when photography transitioned from film to digital and changes were made to many DSLR cameras that affected the focal length of common lens sizes. When pairing a digital camera with a lens, it is important to know whether or not a focal length multiplier needs to be considered. It could dramatically affect the lens that you purchase because you could be buying a lens that does not meet your specific needs. A full-frame sensor has dimensions of 36mm x 24mm. If your sensor is smaller than that, you need to calculate your focal length multiplier and apply it to the focal length of the lens you’re using to get the 35mm equivalent focal length. You may also see the focal length multiplier referred to as the crop factor. Thanks for your support and do visit nitrio.com for more apps for your iOS devices.
ZoneCalc
This app assists photographers in precisely calculating exposure and tonal placement using Ansel Adams' Zone System. It offers features for metering, reciprocity correction, and development adjustments, with options for multi-point measurements and data export.
- Zone System exposure calculation
- Multi-point metering
- Reciprocity correction
- Development adjustment recommendations
- Film-specific development times
- Calculation history and export
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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.
Screenshots
Verdict
The clearest difference is price: ZoneCalc at Free against Focal Length Calculator's $2.99. ZoneCalc also leads on update cadence (every 3 weeks vs every 38 months). Focal Length Calculator's advantage is in-app purchases (none vs 1) and device support (3 vs 1). On ads there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
ZoneCalc is free to download; Focal Length Calculator costs $2.99 up front. ZoneCalc sells 1 one-off in-app purchase. Focal Length Calculator asks for nothing beyond the download.
Focal Length Calculator ships an update every 38 months, ZoneCalc every 3 weeks. The most recent releases landed on September 11, 2026 and September 9, 2026 respectively.
| Parameter | Focal Length Calculator | ZoneCalc |
|---|---|---|
| Price | $2.99 | Free — better |
| Rating | — | 5.0 (2 ratings) — better |
| Number of ratings | — | 2 — better |
| Update frequency | Every 38 months | Every 3 weeks — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | — | Freemium |
| Devices | iPhone, iPad, iPod — better | iPhone |
| Requires iOS | 12.0 — better | 17.6 |
| Further details — not scored | ||
| Size | 9 MB | 3 MB |
| Age rating | 4+ | 4+ |
| Developer | Heng Jia Liang | Juergen Suk |
In-app purchases
Focal Length Calculator
No in-app purchases
ZoneCalc
- ZoneCalc Pro$3.99
Questions
Is Focal Length Calculator free?
Is ZoneCalc free?
Do Focal Length Calculator or ZoneCalc have ads?
Which is updated more often, Focal Length Calculator or ZoneCalc?
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