light meters:

Android: android ligt meter free (light meter – lite)

IOS: Lumu light meter

Film development:

:
https://darkroom-solutions.com/
https://www.digitaltruth.com/devchart.php

Fotográfiai optika

Sümegi András – weekensciencejobs:
https://weekendsciencejobs.wordpress.com/category/foto/
Photographic lens design – wikipedia:
https://en.wikipedia.org/wiki/Photographic_lens_design