Production

Quasar Tube Photometrics

I finally put a light meter on these LEDs

Quasar Science Q-LED tubes have a very popular new lighting option, but oddly enough Quasar doesn’t offer any photometric output data on their website.

So after hearing this question far too many times, I finally put a meter on my standard 4′ Quasar Q-LED crossfade tubes. I’ll update this post in a few weeks with photometrics on the 2′ crossfades, and the 4′ switched bi-color versions as well.

The 4-foot crossfades have a color temperature dial that ranges from 6000k to 2000k. I metered a single 4-foot tube in footcandles at 6000, 4800, and 2000 kelvin settings at distances ranging from 1ft up to 12ft from the fixture. Crossfades seem to deliver the most output at the daylight end of the spectrum. Here are my results:

@ 6000 kelvin
1ft – 320fc
3ft – 90fc
6ft – 30fc
12ft – 11fc

@ 4800 kelvin
1ft – 300fc
3ft – 84fc
6ft – 26fc
12ft – 10fc

@ 2000 kelvin
1ft – 190fc
3ft – 52fc
6ft – 16fc
12ft – 6fc

And for folks interested in modifying Kino Flo fixtures with Quasar tubes, Rob Macey provides the following photometrics on six Quasar tubes in a 4×4 Kino shell at 10ft distance: f5.6 @ 640 ASA. That’s about 60 footcandles on subject, almost twice the output of a standard Kino flourescent 4×4 at the same distance.


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Matt Jeppsen is a working DP with over a decade of experience in commercials, music videos, and documentary films. You can view Matt's cinematography reel and contact info at www.mattjeppsen.com

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Robert

Super useful!