Metriflash

Metriflash is a guide number flash calculator for film photographers shooting with manual flash. Set your flash's guide number, ISO, and distance — the app shows you the correct aperture directly on a sliding scale, just like a light meter. Adjust flash power and exposure compensation, and the scale shifts in real time. Save multiple flash profiles to switch quickly between different units or setups. No batteries, no metering — just math that works.