Reciprocity Timer Downloads & RevenueReciprocity Timer · App Store

Manage your film photography from start to finish! 
Reciprocity Timer has 2 Version - the "Standard" Version does NOT include advanced features but can be used to calculate reciprocity on a range of common films. The "Pro" Version is available for an additional $9.99 USD (via in-app-purchase) unlocks a range of advanced features.
The initial purchase price allows you to calculate reciprocity for all the films included by selecting an observed exposure time. This $1.99 US non-pro version is suitable for people who just need to calculate an exposure that includes reciprocity adjustments for commonly used films. It will suit many users who don't require or need to upgrade to the pro version for features like note keeping or a camera database etc. It's most suitable if you are new to film.
More advanced film users and photographers may want to pay to upgrade after their initial purchase to the pro version. If you use a pro-feature you'll be prompted to upgrade for an additional $9.99 US.
This will unlock all the additional features including the Zone Editor, Note, Camera and Film Holder database as well as custom films and filters.
There is no need to upgrade if you just want to calculate and time reciprocity for a particular film and you always use the same camera.
The app includes in-app purchase to unlock pro features including a note-keeping feature, the ability to add custom films and the ability to select often used film stock as favorites.
Once you upgrade then the one app does it all - notes, filters, exposure calculations, custom films, zone system editor, film holder management as well as the reciprocity math!
A comprehensive film reciprocity calculator for photographers. Select a film type and metered exposure time - the calculator will provide a reciprocity compensated exposure time. The app includes an exposure timer so you can time your long exposures. You can also use a slider to adjust exposure when you have filters attached.
The app supports a wide range of film stocks and allows the user to add various common exposure filters such as NDs and Polarizers.
Keep detailed notes and share them. Share your adjusted exposure times with colleagues.
This app makes film photography a breeze.

You may need to setup Reciprocity Timer in Settings -> Notification Center to ensure the app's timer can notify you when exposures are ending and your device is asleep.

Watch companion app now included. To install the app use the Apple Watch App on your phone. Ensure your watch and phone are paired an unlocked and scroll down the list of available apps to Reciprocity Timer. Select Install. You can also turn on "Automatically Install Apps".