Thursday, March 1, 2012

Long Live Lamps

Time to delve into the lighting world a little bit.  A little bit ago my friend Miles was up from Prism Projection which I wrote all about in this post.  Some of the many side tangents that we got in to were the field of a leko and lamp life.  Two seemingly not-all-that-related topics but here's how they tie in.

LED fixtures far outperform tungsten sources in the area of lamp life.  In comparing the two he brought up the fact that the HPL lamps in my fixtures have a life of about 250 hours.  I mentioned that I had been using a long life variety that had a 1500 hour lamp life.  This is where I got the benefit of Miles sitting through a long and agonizing class on the anatomy of lamp failure and learned a whole lot in two minutes.

A leko, for those not familiar, is one of the lights commonly seen in performance venues that is long and barrel shaped and is capable of throwing light a fairly long way.  There's a lamp in the back and a reflector and a pair of lenses that are described as ellipsoidal.  Theatre folks call them lekos for short.  The position of the lamp in the reflector has a lot to do with how good the light looks when it finally hits the stage and you can adjust its position in a process called bench focusing.

To make a very long story a little bit shorter, I had been having no luck bench focusing my lekos and was looking at some very lumpy fields on my stage.  The reason for this, Miles explained, is that to make the lamps last a little longer, they're made a little longer, which helps with heat in the filament.  Because they're longer, less of the filament is in the ideal position relative to the reflector.

So the moral of the story is, when you're lamping your lekos, spring for regular life bulbs or you'll be looking at lumpy fields for a very long time.

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