Your film camera meter died. Your iPhone already has the replacement.

Light Meter Pro turns your iPhone into a classic match-needle exposure meter for 35mm, 120, and large-format film. Set ISO, aperture, and shutter, then center the needle.

Includes reflected, incident, and spot readings, reciprocity correction, saved camera and film profiles, and a shot log. Works offline. No subscription.

Try it free: https://apps.apple.com/us/app/light-meter-pro-film-cameras/id6790240977?ct=reddit_lightmeter_problem_v1&mt=8