People plan events and ask if I could cover them. The technically most important open question for me is: "Will there be light?" I won't break even by spending time and money to scout venues in advance and don't have a bag full of Sony A7 S IIs & insanely fast glass yet. So I am wondering: How could I make use of clients' iPhones & Android counterparts to dodge dim jobs or make sure they 'll rig up enough stage lighting? What are usable free or dirt cheap exposure- or Lux meter apps that I could ask them to use while picking their venues? Thanks in advance.