The lumens per watt can be seen on the Venture Lighting website-there was a client wanting a new lighting system-they were going to use LEDS,but Venture proved their Metal Halide lights could give better lumen per watt-and indeed they did!so the customer went with Venture.They make excellent products-and good to deal with-I can order anything I need from them!The high lumens per watt with HPS can be gotten with premium quality ballasts such as Constant wattage auto transformer,magnetic regulator and best----Digital switching ballasts.And often digital ballasts c an be used with other HID bulbs-such as metal halide-I have a couple digital ballasts-They run 400w HPS or metal halide bulbs-probe start and pulse start.Unlike magnetic ballasts-digital ones have a "feedback" system that monitors the arc current and voltage and adjusts these as the bulb ages or type of bulb.Some digital ballast can run combination bulbs-they contain two arc tubes- a HPS one and a metal halide one.Greenhouse users love these types of bulbs.Gives the wide range spectrums of light plants like to grow efficiently.
Mercury and High pressure sodium bulbs are favorites for street lighting--long life,constant light output over the age of the bulbs-and the least color shifting.I think someone went too far in "banning" Mercury lights-they are efficient,economical,and have long life.The amount of mercury in the arc tubes is tiny--not worth worrying over.And phospor coated outer bulbs give them a white or warm white color-like flourscents-Mercury bulbs beat incandescent and halogen many times over for efficiency and bulb life.Stupid regulatory folks!!!Many lighting fans are up at arms about this.Its pretty dumb.clear mercury bulbs are the ones thart give the bluish-greenish light-arechetecturral lighting is what these are used for.I was shocked to see the lumen per watt figures for LED vs HID-HID can still win!!But LEDS are getting better-note the types of LED portable lights on the market-there is a portable one that can generate 15,000 lumens!!What a raccoon light that would make!!!Shine that sucker into the trees and the 'coons will drop out of them from blindness!I am trying to remember the maker-It can be seen on the Candle Power forums.I like 35W Xenon-xenide HID bulbs for portable lights---These are essentually HID car headlights in a hand held form.