To return to a point in the original post, the OP mentioned having a metering app for his iPhone. In my experience, the free light meter app for the iPhone does a bang-up job of metering, provided you know how to use it. It's the rough equivalent of a 5-degree spot meter, and you can use it to very quickly determine the SBR of a scene by moving the metering circle around on the screen. It's not a Minolta, Sekonic or Pentax 1-degree spot meter, but it's something you can (and most likely will) always have with you. I don't know that I'd use it for metering really long exposures at night, but I haven't tried that yet. THOSE are scenes I do reserve for the good hand-held meters that I can calibrate.