Is there an app for Android phones to calculate exposures with ND filters?
Chris says… These apps are useful for trying to work out an exposure when using a Lee Big Stopper or another high-density neutral density filter which can be used to lengthen the exposure by up to 10 stops.
I use LongTime Exposure Calculator on my Apple iPhone. Unfortunately this free app doesn’t have an Android version, but I think I have tracked down something similar that will do the trick on your Nokia Lumia 625. It is called Exposed, and it is available through GooglePlay for Android devices. It’s also free, and looks like it is highly rated by those who have installed it.
Find exactly the right exposure length with the help of a free phone app