# Red Filter Film for Headlamps



## jonathanluu2 (Feb 21, 2013)

While there is a thread around talking of a red light for astronomy, I think my question is a bit different. I like to re-purpose my lights as much as possible so I was wondering if there was a red film I could use to stick to the glass of my normally-white-light headlamp? Similar to DC Fix, but instead of diffusing, it filters only red light? I would rather buy a nice adhesive film that I could cut, add and remove as needed for a couple bucks than buy a whole new lamp.

My particular use would be for a modified H51Fw rear light while biking in all weather conditions.


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## SemiMan (Feb 21, 2013)

I would suggest a craft store as the most obvious solution, but if you want to get more "technical", then films used to theatre illumination are available in a ton of transmission characteristics. Personally I deal with Rosco (www.rosco.com). They have the pass spectrum of their filters on their web page.

Semiman


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## JCD (Feb 21, 2013)

Filters are subtractive. If you put a red filter on a light, it filters out all of the light that isn't red. Most white LEDs produce little red light compared to the quantity of "cooler" colors of the spectrum they produce. If you place a red filter on an LED based light, the resulting output level is likely to be disappointing.


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## Bolster (Feb 21, 2013)

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## Mr Floppy (Feb 22, 2013)

Before it gets all too technical here's what I've used:
Photography filters, red cellophane, transparent red book protector sheet, a bit off a smashed rear brake light from a car I picked up off the road, red perfume vial made from glass and even the red filter from Fenix. Affixing these to the light was interesting to say the least. I used to stick this on the Fenix MC10 which had a flip down diffuser, except the diffuser is a bit fragile and broke after a short drop.

Easiest of all was transparent red sticky tape but that was so hard to find! It is sold as automotive lens repair tape. Just very rare here so bought it online from the US (after finding a store that shipped internationally and cheaply). It does diffuse a little bit though but it's so easy to stick on and peel off. My purpose for this was to use as a rear light too for my bike.


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## jonathanluu2 (Feb 22, 2013)

LOL night vision goggles on my bike haha. All valid arguments that I have seen so far. I wasnt trying to light up the world with the filter on the light, just provide a blinking strobe that wasnt white and possibly be misleading to other vehicles on the road (light color valid for USA, perhaps different where you come from). I was hoping that with my neutral white light that I would get a more desirable output in the red spectrum. 

I like the transparent red automotive tape, as it would be easy to apply/remove. It is less than $5 here in the USA. In all likelyhood I will try that out just to see what happens when i have a 100+ lumen strobe blinking through it. In the very least I can report back my results in the name of SCIENCE!! IF that doesnt work I will probably just buy a cheap red LED light. I just cant justify getting a nice $30+ dedicated red LED light that I wont use every day.

Thanks all for input so far.


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## SemiMan (Feb 23, 2013)

jonathanluu2 said:


> LOL night vision goggles on my bike haha. All valid arguments that I have seen so far. I wasnt trying to light up the world with the filter on the light, just provide a blinking strobe that wasnt white and possibly be misleading to other vehicles on the road (light color valid for USA, perhaps different where you come from). I was hoping that with my neutral white light that I would get a more desirable output in the red spectrum.
> 
> I like the transparent red automotive tape, as it would be easy to apply/remove. It is less than $5 here in the USA. In all likelyhood I will try that out just to see what happens when i have a 100+ lumen strobe blinking through it. In the very least I can report back my results in the name of SCIENCE!! IF that doesnt work I will probably just buy a cheap red LED light. I just cant justify getting a nice $30+ dedicated red LED light that I wont use every day.
> 
> Thanks all for input so far.



If it is multimode, you could consider replacing the white LED with a red LED. I would not do that with direct drive as the forward voltage of the red is likely quite a bit lower. Multimode as it would likely be wayyyy to bright otherwise.

Semiman


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## roddyjb (Mar 28, 2015)

Is there any 2-3mm thick filter sheeting I can cut my own circles out of. This is for some accent lighting, not on a flashlight or photography use but the same colour filter sheeting would be great. I need to make some circles about 45mm or 1 & 3/4".

Thanks.


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## RedLED (Jun 3, 2015)

Here is your answer. 

It it is called Gel, or theatrical gel.

go to a professional camera store, if there any left, and ask for a sample gel kit. The have hundreds of colors and the red you need is in there, no doubt, blue and green too. Also many wonderful diffusion gels. 

All free. If you don't have a store, call B & H, New York, and ask the lighting department for a Roscoe sample kit.

if not, PM me and I will send you one from my plush, well lit, high tech, ultra spacious, heavily decorated studio.


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## chumley (Jun 3, 2015)

I used to be a lithographer and worked with film. We used a red tape made by 3M that came in rolls usually 1/2 inch width. If any one is still using film it might be available at printing supply companies. Getting theatrical gels is a good idea, I got some gel sheets at theatrical sound and lighting store.


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