Support
Contact
For bug reports and questions, please email:
takumin.develop@gmail.com
It helps if you include your iPhone model, iOS version, and the app version (Settings → About; このアプリについて in Japanese).
FAQ
How is the focal length calculated?
FocalCalc uses the angle of view reported by the iPhone camera and calculates the focal length that gives the same angle of view on the selected format (sensor size). Lens distortion and device differences may cause small differences from real cameras.
What is the difference between "diagonal" and "long edge"?
"Diagonal" matches the angle of view along the diagonal, the same idea as the "35mm equivalent focal length" recorded in iPhone photos. "Long edge" matches the width in landscape orientation, which is useful when comparing formats with a different aspect ratio (such as 6×6). You can switch the basis in Settings.
Can I add my own camera?
In Settings, go to the formats section and add a custom format by entering the sensor width and height in millimeters. The camera screen shows up to five formats, including the main one.
Where are the values recorded in my photos?
Open the photo in the Photos app and swipe up (or tap ⓘ). The caption shows text such as "FF 24mm | APS-C 16mm (diag, FocalCalc)". The focal length (mm) shown in the info panel is the full-frame (diagonal) 35mm equivalent. Photo apps that show EXIF data and descriptions can also display the "35mm equivalent focal length" and the caption.
Can I add the values to the image itself?
Turn on the burn-in option in Settings to draw the text in the bottom-left or bottom-right corner. The camera preview shows the text that will be drawn. You can also choose to save a copy without the text.
Photos are not saved
In the iPhone Settings app, open FocalCalc → Photos and make sure at least "Add Photos Only" is allowed.
Why is image quality lower than the built-in Camera app?
Third-party apps cannot use all of the image processing of the built-in Camera app (such as Night mode). Please use FocalCalc as a tool for checking and recording the angle of view.
Can I change the file format?
Yes, choose HEIC or JPEG in Settings.
How do I change the app's language?
FocalCalc follows your iPhone's language (English or Japanese; other languages show English). To change it for this app only, go to Settings > Apps > FocalCalc > Language.
Requirements
iPhone with iOS 17 or later (rear camera required). The app works in landscape orientation. The interface is available in English and Japanese (it follows your iPhone's language).