Red-Orange vs Red Through Red Filter

When using an LED behind a red filter would red-orange be more intense than red? Typically red-orange are rated higher in lumens vs red at a given drive current, but will red-orange still over come losses through a red filter to prevail?

The purpose of red light is to preserve night vision.

I am just asking what would appear brighter to the human eye through the red lens? Red-orange or red? Is there enough losses that red-orange is not a better choice behind a red filter per say.

jerryoh said:

When using an LED behind a red filter would red-orange be more intense than red? Typically red-orange are rated higher in lumens vs red at a given drive current, but will red-orange still over come losses through a red filter to prevail?

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The simple answer to your question is it would basically be the same if there was no filter at all. Both the red and red-orange will pass through the filter. If you use a red-orange LED behind a red filter, the light will most likely still be red-orange, more orangish than if an incandescent bulb was used behind the filter.

jerryoh said:

When using an LED behind a red filter would red-orange be more intense than red? Typically red-orange are rated higher in lumens vs red at a given drive current, but will red-orange still over come losses through a red filter to prevail?

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Did you not ask this in the Automotive forum and got shut down because creating your own brake/tail lights for a road going vehicle is illegal?

jerryoh said:

I am just asking what would appear brighter to the human eye through the red lens? Red-orange or red? Is there enough losses that red-orange is not a better choice behind a red filter per se.

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This is of general interest to the LED hobbyist, no mention of motor vehicles or attention-grabbing garments either, therefore I cannot see why your question should not be legitimate in this forum. I once had a red-lensed red + orange-red LED light (safe and legal on a road-going bicycle in America and elsewhere.) Unless the red filter is unusually tinted, the orange-red is likely to look brighter. But I don't think it's worth it. To me, personally, the orange-red LEDs lights look "cheaper" in traffic. On the other hand, don't rely on very-deep red because it might not work with some ophthalmological variants or knucklehead sunglasses.

jerryoh said:

When using an LED behind a red filter would red-orange be more intense than red? Typically red-orange are rated higher in lumens vs red at a given drive current, but will red-orange still over come losses through a red filter to prevail?

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sounds like a good excuse to run an experiment.... let us know how it turns out.

to add some background... I think it is all going to depend on the particular characteristics of the specific LEDs and red filter that you are working with. My guess is that red-orange light won't be significantly attenuated by the red filter.

SemiMan said:

Did you not ask this in the Automotive forum and got shut down because creating your own brake/tail lights for a road going vehicle is illegal?

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I suppose that was because I mentioned automotive lighting in my example. It was shutdown with no chance given for further explanation. In the early days of LED CHMSL they used red-orange LEDs to match the color of a filaments behinds a red lens from my understanding. Now days I am assuming manufactures use red LEDs behind a red lens in all cases so everything matches. I was just curious what what color was actually brighter and more receptive to the human eye given a red-orange LED is typically rated 'brighter' v a red LED at the same drive current. Perhaps it was a poor example. Hopefully this thread does not get shut down for mentioning automotive lighting for an example.

In view of the varying specifications of red LEDs, of orange/red LEDs, and the varying types of color filter that exist, I don't think that this can be reliably resolved without a practical test involving samples of the LEDs and filters proposed.

Use of suitable LEDs WITHOUT a filter has the merits of simplicity. If quantity production is being considered rather than a DIY "one off" then an un-filtered LED has the advantage of only having to worry about the LED specification changing in time, and not having to worry about the color filter also changing.

As others have stated, DIY automotive lights are a big no no at least on public roads.
Manufacturers can of course make new designs of automotive light, but the testing and approval regime is strict, expensive and not realistic for the hobbyist.