myLightMeter PRO vs Zone Tool

Designed by a photographer, for photographers. Built for reliable, precise exposure measurement across film and digital workflows. myLightMeter PRO gives you full control over exposure through a clean, professional set of tools. Key Features • Incident and reflected-light metering • Classic and Pro interface styles • Full manual control over aperture, shutter speed, ISO, and exposure compensation in 1/3- or 1/2-stop increments • Exposure range from 4 hours in Long Exposure mode to 1/8000 s, f/1.0 to f/512, and ISO 0.8 to 409,600 • Aperture-priority (Av) and shutter-priority (Tv) modes • Automatic ISO adjustment or ISO lock • Reciprocity correction for long film exposures • Sensitivity down to −2.5 EV, ideal for low-light scenes • Average multiple readings • Import shutter speed, aperture, and ISO from photos in your library • Organize readings into Sessions with photos, exposure data, camera and lens details, and notes • Keep your Sessions synced through iCloud, so they remain available when you switch phones or use another device • Export Sessions as PDFs or print them Advanced Tools • Hyperfocal-distance calculator • Five configurable presets, each storing camera, lens, ISO, filter, and film settings • EV display with an analog scale or numerical reading • mySPOTMETER and f/Tools integration About This app is built and maintained by an independent photographer and developer. It is the tool I personally use and continuously refine. If you have suggestions or need support, contact me at: davidquiles@me.com

With this tool you can calculate your exposure and needed adjustment for development. It uses zone system theory originally invented by Ansel Adams and Fred Archer. First decide zone of your shadows and measure the shadows. Then device highlight zone and measure the highlights. Measure these with the film ISO you are going to use. You also need to decide shutter speed in beforehand. The app calculates exposure aperture for you and also tells if you need to shorten (N+..) or expand (N-..) your development time. You will get best results with a spot light meter but mobile apps will probably do fine.