I am interested to hear how you get on with the lightmeter app. I have an android phone and there are a number of lightmeter apps, but....having used the same app on 3 different phones (Samsung, Xiaomi and Nokia 7+) and each gave vastly different readings, i have doubts. Having had that experience I doubt the veracity of lightmeter apps on phones - at least of the Android persuasion. I'll stick with my trusty Gossen Mastersix when using a camera without metering (or in a pinch I'll use my Hanimex PR-45 from 1966, which, surprisingly, is still accurate!)