I have been using LightMeter in my iPhone for the last year or so. Once I understood the protocol, I was able to use the program pretty much as I would use any light meter. The results are consistent and, as far as I can tell, accurate. I prefer to use my Sekonic light meter most of the time because it is faster and easier to use but I am glad to have a meter in my phone when I forget to bring the Sekonic.