Fstop -Photography Calculators

Fstop is a bench of eleven photography calculators that never opens your camera.

Set fifty millimetres at f/2.8, focused at three metres, and it does not just hand you a number. It draws the band: unsharp field, near wall at 2.74 metres, the focus plane, far wall at 3.32, and the note that a quarter of a metre of it sits in front of your subject and a third behind. Stop down and the band grows in front of you. The hyperfocal distance sits alongside, and a table gives you the same figures at every aperture on the lens.

Light is one triangle. Lock the ISO and moving the aperture moves the shutter; the app lists every equivalent exposure of your reading and tells you what each one costs you — thinner focus here, visible motion there, diffraction from f/11. Stack a three-stop filter on a ten-stop filter and it adds the stops, shows the arithmetic and tells you to switch to Bulb for two minutes and seventeen seconds.

At night it takes the 500 rule seriously enough to argue with it. On a forty-five megapixel full frame at twenty-four millimetres, five hundred divided by the focal length gives you almost twenty-one seconds — and visible trails. The NPF rule, computed from your sensor's actual pixel pitch, says eight. Fstop draws you both, as a small field of stars streaked by exactly the amount the arithmetic predicts, and lets you decide.

There is also a coverage cone that tells you the frame is 2.16 metres wide at three metres, a flash guide-number tool with the inverse-square ladder drawn out, a time-lapse planner that turns an hour and twenty of standing still into fifty seconds and warns you it will cost thirty-three gigabytes, and a shelf of saved setups you can name and load back.

Every formula the app uses is printed on the About screen. If the code and that screen ever disagree, the screen is right.

Fstop requests zero Android permissions. It does not open the camera, read your photos, know where you are, or contain any network code at all. It ships no camera or lens database, so nothing in it goes out of date. You describe your body once — format and megapixels — and it derives the pixel pitch and the circle of confusion itself.

It is dark on purpose, and it stays dark.

KEYWORDS:
depth of field calculator, hyperfocal distance, exposure calculator, ND filter calculator, long exposure, 500 rule, NPF rule, astrophotography, flash guide number, field of view, crop factor, time lapse calculator, offline photography tools

DATA SAFETY DECLARATION:
- Data Collection: No data collected.
- Data Sharing: No data shared with third parties.
- Network Access: Zero network permissions (100% offline).
- Tracking: Zero analytics, zero ad SDKs, zero crash reporters.
- Storage: 100% local on-device SQLite database and SharedPreferences.
- Camera / Photos: No camera access, no photo access, no MediaStore queries.

HARDWARE & PERMISSIONS DECLARATION:
- Camera: Not used (no CAMERA permission requested or declared).
- Location: Not used (no GPS or network location).
- Storage: System Storage Access Framework (SAF) only for document export.
- Notifications: None (zero notification permissions).
- Declared Permissions: ZERO ( count = 0).

ADS & MONETIZATION:
- Contains Ads: No
- In-App Purchases: No
- Subscriptions: No