Even Redder, Even Dimmer!

lampeDépêche

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May 15, 2012
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Abstract: I got some deep red LEDS, and put them into my Photon. I like the result!

On a recent thread, I was touting the advantages of using a Photon Freedom for preserving night-vision.

I am not an astronomer, but I do read in bed at night, and my wife doesn't want bright lights waking her up. In addition, I have read reports that certain kinds of blue wavelengths, in certain intensities, can stimulate wakefulness, whereas I'm trying to read myself to sleep. So for all of these reasons, I like a dim red light. And I can clip the Photon Covert Red to my glasses and never notice the weight.

But on other threads, I have also seen people say that the common "reds" you find in e.g. the Photon and other LED lights are not true reds, but only oranges. And they may not be red *enough* to get all of the good effects of red light. This seemed strange to me, because it sure looks red to me. But the people talking about its orangeness are people whose opinions I trust.

So I tried an experiment.

I bought some 660nm 5mm LEDs from an online supply company. Dirt cheap--about 50 cents a piece.

It was not hard to take apart the Photon, pop the old LED out the front, trim the legs on the new one, and install the new one in the Covert shroud--5 minutes tops.

The good news: it's really much redder! When I use the new 660 red for a while, and then turn on the standard Photon Red, it is *so* orange, almost yellow, that I can't believe I ever thought it was red!

The mixed news: it is a *lot* dimmer, at any power level. This is spec'ed into the LED: the supply company sells a 630nm which is rated at 10,000mcd. The 660nm is rated at 2,000mcd. Yes, part of that is a difference of angle in the bare emitter--the redder LED has a wider angle. But there is also a difference of total lumen output. And the wider angle gets gobbled up by the Covert shroud as well.

It's a lot dimmer. Still plenty to read by, but I'm running it on full power, instead of maybe half-power as I used to with the orange/red emitter.

On the whole, though? I like it. If you want genuine deep red, and if you want dim in any case, then do this simple swap. You get an even better low-level red than the unmodified Photon Freedom was to start with.
 

Bolster

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... it's really much redder! When I use the new 660 red for a while, and then turn on the standard Photon Red, it is *so* orange, almost yellow, that I can't believe I ever thought it was red!

That's interesting! So a person really needs a "red reference" then, yes?
 

lampeDépêche

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That's interesting! So a person really needs a "red reference" then, yes?

The old one was totally, obviously red. Until suddenly it wasn't at all, when compared to the new one. It was startling.

And it made me think:

"This, in a nutshell, is why there is endless disagreement on CPF about tints. And this, in a nutshell, is why most of it is pointless."

When even my own eyes couldn't agree with what they had insisted on 20 minutes ago, how are two different pairs of eyes in two separate lighting environments with different color samples all around them ever going to agree?

People should either switch to purely photometric discussions, with a lot of numbers involved, or just drop it.

"Yeah my new Gonzolight was supposed to be a perfect neutral but it's a puke green--so I sent it back!"
"No way--I like greener tints, but my Gonzolight is this gross rosy pink color--so I sent it back!"

No wonder the manufacturers throw their hands up in despair.
 

eh4

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Oct 18, 2011
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This would be a great post to have pictures. Might be tough to photograph though without a quality camera and manual exposure.
Test pic of each at whatever level you thought they were equally bright at, a pic of each on their own at same level and a pic of each at highest setting, and maybe one of them together at high and low.
 

Sub_Umbra

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Mar 6, 2004
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la bonne vie en Amérique
Anyone wanting to experiment with dark adapted vision should check out the lights at Rigel Systems. Their output is controlled by a thumbwheel and may be dialed down very low. Leon (owner of Rigel Systems) teaches astronomy and also invented the lights he sells. He stocks deep red LEDs at 660nm and his Starlite Mini actually has sockets for the LEDs so you may unplug the LEDs that came with the light and plug in another color for experimentation without having to buy another light.

I recall Leon saying that you could email him and put together an order for a light and some additional LEDs in different colors.

I have a Rigel Systems Mil-Starlite (blue-green). The military's Night Vision Lab at White Sands has certified the Mil-Starlite as compatible with night vision devices and as of a few years ago it was the only commercial light so certified.

Keep your old 630nm light for the next time you get a wood sliver. It is the perfect wavelength for digging out slivers.
 
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uk_caver

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Feb 9, 2007
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For a cheap non-variable-power version, the bargain (10 for ~$6 from the usual far east suppliers) 5mm led keychain lights are easy to pop coloured LEDs into.

I used some to make some red LED survey targets for caving use - it's handy to have an illuminated point to aim a compass or clinometer at, and having a red target avoids possible confusion with the light of the person holding it.
To keep the brightness down and runtime long, I removed one of the cells from each light, and added a series resistor to the LED.
I soldered a small axial-leaded resistor onto the LED leg on the non-switch side of the light, with the other lead of the resistor bent round through 270 degrees so it passed underneath the middle of the resistor body. The resistor keeps the LED leg from contacting the cell (saves having to insulate it), and the resistor body provides pressure to hold the curved lead pressed against the cell.
 
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