Surefire L1 Red - weird filter discovery

So I got a 2007 Red L1 in the mail today. Not super into the Kroma, but I enjoy having red leds around for night time stuff (not waking my wife and keeping my night vision, etc.).

I was playing around with it and trying different filters and discovered something really weird - a blue filter blocks nearly all the light. Only on high can you see a tiny red spot .5 lumens maybe. I was expecting purple light - whats going on here? Showed it to my wife and she expected purple also. Led experts - whats happening with the red leds and blue filter?

So for those interested - I'd pick up a Red L1 sometime if you want a nice low and very bright high red led. The colored L1s are the 2007 non-cree models. The new cree L1s don't come with the colored leds option when I checked the Surefire site. I would bet the colored L1s are discontinued or far off - but don't quote me on this. The A2 comes with red leds as an option and the Kroma has red too, but I enjoy the L1 form factor and throw with the option of using a white diffuser to create a nice red flood. It's a great light that I was hesitant on getting, but am very happy with my decision.

A red LED only creates red light. So any other color filter should block most of the light.

An incan with a red filter still has some blue coming through so a blue filter and the red filter added together will make a purple filter so the color that comes out is purple.

Thanks for the info! That makes sense to me. So only red light coming from a red led, no other color at all. Very cool info on leds and incandescents. :thanks:

Had you mixed the beams of red and blue flashlights, purple would be the result since this is additive.

When you progressively add filters your in a subtractive situation.

Two different aspects of color theory.

LED museum has lots of color spectrum graphs show what kind of light LEDs, incans, and various other lights actually put out. http://home.att.net/~ledmuseum/specx01.htm

Cool graphs! It's neat to see the wavelengths of the colors. Colored leds are pretty cool. Didn't really understand them until this thread.

Just tried a red filter on my 2008 Cree L1 white and the output was terrible. Very low and no punch at all. Must not be that much red in the cree wavelength for the filter to show?

Never really knew how bad white leds did with colored filters in comparison to actual colored leds. Very interesting. I'm always learning something around here!

A white LED is a blue die with a yellow phosphor, so most of the light that comes out is blue and yellow. All of the visible spectrum is there but most of the other colors don't have much punch.

Look at the graphs, the red part is all that got through the filter, and that's why it was so dim.