Light Ruler: Photo Toolkit

Calculate ND exposure, depth of field, night sky shutter, and angle of view in the field. Local-first and account-free.

Light Ruler is a local-first photography calculator designed for iPhone. It is useful for landscape, long exposure, night sky, and everyday exposure planning.

You can quickly calculate:

• ND filter long exposure shutter speed
• Equivalent exposure for aperture, shutter, and ISO changes
• Depth of field, near limit, far limit, and hyperfocal distance
• Maximum night sky shutter before visible star trails
• Angle of view and equivalent focal length across sensor formats

Light Ruler does not require an account, does not connect to a backend, and does not actively make network requests. Camera profiles, lens profiles, and saved calculations are stored locally on your device.

Useful for:

• Long exposure with ND filters
• Night sky shutter planning
• Landscape depth of field and hyperfocal checks
• Comparing focal length behavior across sensor formats