Red filter question

Does putting a red filter over a white light actually block all the other colors from passing through? I need a red light that wont spook animals, and i bought the Red Filter from fenix to use on my P3D. Deer cannot see red but they see blue and purples very well. White light is made up of all these color, so does the filter actually block them, allowing only red to pass through?

Yes, that is how a filter (at least this type) works. All other wavelengths are blocked in this case.

Thanks

I recently used a red filter on my E2DL to track skunks that were getting under the house. It worked great and the skunks never even flinched.

It will also depend on the light spectrum of the LED or Incan. It may be very white or blue, but not contain much light in the red spectrum.

I tried the red filter on an LX2 and it was very dim - too dim to be useful at 200 lumens other than reading 6 inches away.

I think that there is not much red in the LX2 LED - perhaps more blue type spectrum. As a result the red filter blocked almost all the light.

I think I have seen a comment that a red filter will work better on an Incan since it is warmer and has more red light.

I think the same applies to IR filters.

Ace,
Don't give up on the H501R. I just posted some answers to some of your questions in the headlamp forum.

I recently used a Red filter on my Surefire LX2 and it worked great. You will lose some of the output, but I could still light up objects at about 40 feet (LX2 on high).

the most effecient way to produce red light from an led is to replace the white emitter with a red emitter. cree xr-red are about 630nm

here's a couple of mods I made some time ago, the one on the left is filtered with yellow camera lens filter simply to remove the blue spectrum. Look closely in the reflector on the right & you can see the red emitter

There is plenty of red in an XR-E.

Think about it, if there weren't reasonably even amounts of red green and blue, a white LED would not look very white.

Cheapskate said:

There is plenty of red in an XR-E.

Think about it, if there weren't reasonably even amounts of red green and blue, a white LED would not look very white.

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Actually there is very little red. LED's spectrum are weighted far more to the blue side of the spectrum (even "neutral/warm" ones).

Cheapskate said:

There is plenty of red in an XR-E.

Think about it, if there weren't reasonably even amounts of red green and blue, a white LED would not look very white.

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relative to a red emitter designed to produce only red light, a white emitter produces very little red light & also draws more current because its producing other colors of the spectrum that may not be required

if red light only is required from an led then a specefic emitter for that purpose will be the most effective

Marduke said:

Actually there is very little red. LED's spectrum are weighted far more to the blue side of the spectrum (even "neutral/warm" ones).

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I think your idea of very little is not the same as mine.

I frequently use my NDI with a red filter on it's lowest setting, which I think is 5 lumens and it provides plenty of light for me to see by. On full output, it lights up a room in red light. Here it is on max - photo taken with my phone.

lightforce2 said:

relative to a red emitter designed to produce only red light, a white emitter produces very little red light & also draws more current because its producing other colors of the spectrum that may not be required

if red light only is required from an led then a specefic emitter for that purpose will be the most effective

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I am fully aware of that and in fact made a carbon fibre torch with three high power red emitters in about 1995

The NDI + filter kills it in total output and efficiency due to technical improvements over time.

Just look at the spectroscopy of a white LED and see how little red there is in it. Filtering a white led to output only red blocks 80-90% of total output.

Cheapskate said:

I am fully aware of that and in fact made a carbon fibre torch with three high power red emitters in about 1995

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I think we're on different wavelenghts here. I didn't know cree were making XR-E Q5's and XR-C Red's in 1995.:duh2: You have to compare apples with apples

most lights will produce some red that becomes quite visable when the remainder of the spectrum is filtered out however not all of these would be suitable for the usage as requested by the original post which was about finding deer in the wild with red light, this is a lot different to finding your way in a room

irrespective of the emitters, how does the NDI with a small reflector + filter provide greater output when compared to either a Derelight DBS or a Tiablo A9. Put a modern Cree XR-C Red red emitter (not a 14 year old red emitter) in any of these and I know which I'd use for deer spotting (as a pest animal shooter I do a fair bit of it actualy)

My best red light is a Lux 3 L1 with stock red emitter. It's super bright and blinding to say the least. Even on low it is very bright. It's almost scary bright.

I agree that the best way to get red from a led light is to actually have a red led light and avoid filters. Seems like the most efficient way to get red.

Seems that using a blue filter with my leds gives much more light. When I try my red filters on the same lights it's disappointing and dim.

lightforce2 said:

I think we're on different wavelenghts here. I didn't know cree were making XR-E Q5's and XR-C Red's in 1995.:duh2: You have to compare apples with apples.

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They weren't, I did not say they were.

most lights will produce some red that becomes quite visable when the remainder of the spectrum is filtered out however not all of these would be suitable for the usage as requested by the original post which was about finding deer in the wild with red light, this is a lot different to finding your way in a room

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My initial post was in response to lxhunter's observation that - "As a result the red filter blocked almost all the light."

Obviously in retrospect I should have quoted his post as you seem to have become somewhat hostile, and assumed that my post was in response to yours due to the juxtaposition.

irrespective of the emitters, how does the NDI with a small reflector + filter provide greater output when compared to either a Derelight DBS or a Tiablo A9.

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It doesn't, and I did not say or imply that it would. I mentioned it by way of example, assuming that with a modicum of thought, one might infer that filtering an inherently more powerful light than the NDI would likely yield a more potent result.

Put a modern Cree XR-C Red red emitter (not a 14 year old red emitter) in any of these and I know which I'd use for deer spotting

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So would I, but if one didn't want to modify a light, one could at least try a filter first and see if it would sufice.

A pure red output LED is more true to a single wavelength in the RED spectrum than any filter material. And not all filter elements are of the same quality and limit the spectrum as much either.

All "white" output LED's are actually blue LED emitters with phosphor coatings to make up the spectrum that will give "white" light. Most of these white output LEDs do not have much in the red spectrum at all. Some have more than others and thus they have different "tints". Some LEDs that are intentionally made to give a "warm" color have much more of the red output phosphors in the mix to give it that warm tint and light up reds such as the Malkoff M60W. I have the spectrums of a few "white" LEDs and there is a heck of a lot more red output in that spectrum of the Malkoff M60W versus most of the "cool" white LEDs that are heavy in the blue output (directly from the LED) and don't go much into the red at all. All of the high output, high efficiency LEDs are biased towards the cooler tints with more blue since its more efficient and get higher lumens numbers that most people crave. A comparable LED with phosphor coatings biased to give more of the red are typically lower in total lumen output. The Malkoff M60W is typically 40 to 50 lumens less than the Malkoff M60 cool running at the same power level for instance. Some makers go for a more balanced "neutral" white in their LED emitter or flashlight package than others and thus there is a pretty good spread of what you can buy, which explains why some guy's "white" LED doesn't look as bad behind a red filter than some others without having specifically bought it for that purpose. But all are much poorer in red wavelengths than any incan light which is very rich in the longer wavelength end of the spectrum.

The point is, if you can't find a good pure RED led emitter or module to drop into your light, you can buy a warm output LED such as the Malkoff M60W and put your red filter in front of that and have a lot more light than from most other "white" LED modules. If you don't want to spend that kind of money for the module then use an Incan that sucks up more power and put a glass red filter in front of that and you will have useable output.