The 211 and 212 bulbs which are common have a 100 to 200 hour rated life, depending on the manufacturer. The Ushio PH213 has a rated life of 3 hours. But given the cost of these bulbs I would also be inclined to just stock up with 10 or more of them and then buy a new one when one burns out.
Originally Posted by Ektagraphic
The Durst bulbs are out of production for the 138S. I don't know how long they bulbs are rated for, but at the cost of finding replacements I want to extend their life as much as possible.
The LED bulbs are all over the place in terms of quality. Also some of them glow after you turn them off. I have noticed this with the Philips bulbs that have the yellow panels, which contain phosphors that are activated by the UV in the LEDs. I have had very good luck using raw LEDs (with the appropriate power supply), but the few bulbs I put in were not particularly successful. But I only tried the ones I had around the house.