Lghtmtr is a simple light meter application for the iPhone to take light readings of scenes primarily for film photography. Lghtmtr is also a great tool for beginners to film photography to learn how exposure, aperture, ISO are all related as the app helps the user visualize these connections.
I developed this application after realizing that I already carry my phone with me where ever I go and because it would be nice to recover the space in my camera bag my regular light meter takes up.
Currently the application is very simple, though a few extra features are in the works. You take a reading of a scene with the camera, either using the iPhone to suggest a good exposure, or by clicking on a region of the camera’s view to better expose for that area. After an initial reading, you can then lock in and adjust the values for shutter speed, aperture, and ISO. Your adjustments will then make the app update the other non-locked-in values.