How bright is the brightest light bulb?
Need a little care here. If you define bulb as being a clear material enclosed object for a length of time, then probably halogen bulb capsules using in stage and theater lighting are the brightest. If you are talking about most peak light, then one of the large strobe lights used for high speed image capture are the brightest, but only for a few thousandths of a second. If you are talking about brightest continuous source, then the arc lights used for film work, most often seen shining on the sky at openings, but they are not bulbs but open electrical arcs which give off lots of fumes that can be seen when they are used outdoors.
