Searching for very low brightness, red LED headlamp for astronomy

[MikeAusC]

. . . . For the purposes of astronomy though, there is more diversity to the problem. When looking at a whole starfield the rods/scotopic vision are most critical and to that end having a fully dark adapted rods is critical. However, when looking at an object of interest in the center to the telescope eye piece, we are not using scotopic vision but photopic vision. . . . .

. . . . but I'm really glad that SemiMan has worked out that for Astronomy, there are in fact two different needs, for which there may be two quite different solutions.

I'd like to add that we use photopic vision for Astronomy not just when looking through the Telescope, but also when observing stars with our unaided eyes. When we see that Mars is red or that stars are distinct points of light, it's clear that they are producing enough light on our Cones to trigger Photopic vision. Those cones where we gaze at the stars are in the Fovea, where there are no Rods to be leached, so we see no "holes" in our nightvision after gazing at a bright star.

 

[rocketsurgeon01]

Streamlight Sidewinder Compact (Sportsman) or Sidewinder Compact 2

 

[SemiMan]

I wonder if the OP got his answer in post #4, a day after he posed the question, and has taken off, never to return.:naughty:

Well if he did disappear, then it has been his/her loss. Fortunately the conversation kept going. Many subtleties to lighting and often you need yours and others preconceived notions to be challenged.

Semiman

 

[kzb]

Wow what a discussion ! I'm not at this level of nirvana, but I'd like to add one thing:

I think there is a big learning component to seeing with red light. It takes practice. The first few times you try it, it is is a bit disorienting and you do not think you can see properly. But as you gain experience, it becomes OK.

Maybe it is a combination of brain visual interpretation training, and also could there be some biological adapation going on? Could your retina produce more of certain pigments to enable better vision in red light?

 

[wbp]

Sadly, it looks like ZebraLight has dropped all of the red headlights from their line. I still have an H30R, which has a wide field lens and comes on at the lowest level with a single button push, but they stopped making that a long time ago. The H31R was available the last I looked, along with other red headlights that used different battery types, but the ZebraLight web site no longer lists any of these.

From what I can tell it looks like the next best choice might be the Princeton Tec Remix (3xAAA) or Remix Pro (1xCR123 - my preference). There is also the Princeton Tec Byte (2xAAA) which looks very interesting, it has only a single red LED but I don't have any idea what the illumination is like. One feature I like about the Remix Pro is that you have to hold the button to switch between red and white output, making it hard to get white light by mistake. The Byte does not have this feature, and if the description is correct must be cycled thru the white modes to turn it off, which would rule it out for astronomy (or any dark adapted) use.

I just ordered a Remix Pro and can post back here once I get it if folks are interested.
William

 

[beast1210]

Worth a quick mention, but as noted above may not be ideal, still a much better light than the energizer offerings. Is the xtar h1/h2

 

[yellow]

I did not follow the whole thread ... so possibly the topic has been already covered:
but as I remember, the actual general agreement is, that it makes no difference if the light is white or red, it is its brightness.

with that in mind, think/look for a lowlowlow white light.
Easier to find than just a red and white light is way more useful ...


as to useful ...
Just 2-3 weeks ago I happened to be invited to a meeting of such astronomy ppl.
They met a some parking lot up on a nearby hill, each of them getting out a man sized "tube",
shouting at anyone with a light (campers at the site, cars driving by at the street, ...) but who have no clue that they even are there (I would have brought some signposts)
and just one or two of the group of 10 telescopes even had lights - the crappiest ones I might have ever seen...
... even on night hikes I dont see such "lights" ...
the one most used was a red led model, but the guys "needed" it for reading where their stars are and the "map" was a mixture of colors and red - and reading red with a red light is a bit difficult.
They ended up with (one of) my white lights in firefly mode - less bright than the red led one - and were much better of...

 

[wbp]

I received the Princeton Tec Remix Pro yesterday. I ordered the 70 Lumen version but what I got was the 100 Lumen version; I'd guess the 70 Lumen is no longer available. Sadly, even on low it's way too bright for dark adapted astronomy use. I am returning it.

I was thinking of ordering the Princeton Tec Remix (AAA version) but given that the description says "100 Lumens" I'm guessing it's the same light with a different battery case.

The search continues...

 

[The Owl]

One possible headlamp is the Petzl Strix, red 1 lumen, green 1.5 lumen, blue 0.35 lumen, white 40, 15, 0.4 lumen. Looks like Darth Vader.. http://petzl-tactical.com/en/headlamps/headlamps-tactical-operations/headlamps/strix-vl

 

[Blue72]

I have played around with red lights and different color lights for years to preserve night vision. But they become very frustrating to use especially in a outdoor environment. I know find .4 lumen white light works best. Am I sacrificing night vision???......maybe, but not enough to notice and I don't have anymore banged up toes and it feels more natural

 

[wbp]

@dd61999 - it sounds like you are looking for a light for a different purpose, not astronomy, since you mention "in a outdoor environment". For your purposes red is probably not the best choice.
@TheOwl - wow, that sure is an interesting looking light, I had not found that in my search. "interesting" from an appearance standpoint, though. At 1 lumen red it's too bright for fully dark adapted astronomy use.

I have given up trying to find something that works, and have now built my own headlamp! It was a fun project and I am very happy with the results. I showed it to some fellow astronomers this past weekend and they all want one! I used an RGB light source, so when it comes time to pack up, if I want white light I can switch to that.

I don't have anything sensitive enough to measure below 1 lumen, but I'd estimate the lowest level red to be about 0.25 lumen, based on a comparison with my ZebraLight H30R on low, which is rated at 0.4 lumen. My new headlamp has one very cool feature which I've never seen before in a headlamp, but you'll have to wait a bit to find out what that is until I've had a chance to do some patent searching...

 

[CactusSeed31]

Hi to everyone. I know this is an older post. but I find it very interesting and informative. Thanks to everyone for sharing their expertise.

For a few years I have been playing with modifying some Chinese White (copies of Photon) microlights for a friend of mine that loves astronomy. These lights normally take 2 CR2016 batteries. With most 5mm RED leds, you use a single CR2032. The CR2032 has around 230mah @ 3 volts, versus the 80mah in a CR2016. A red LED draws about 25-30ma with a new battery. A White LED draws about 65ma with the 2 CR2016. With a single CR2032, the white leds pulls about 7mah. AND are bright enough to read close up and get around indoors. I can't measure lumens, but both the RED and White Led's are way too bright for astronomy use with just the CR2032. I have NOT tried the deep red 680-700nm peak "deep red" leds; but expect that they too might be too bright for best night vision.

I recently took an old GREEN Photon 3 that I had, a replaced the 2 X CR2-16 batteries, with 1 CR2032. The Photon 3 has 3 (PWM) output levels, low medium and high. On low with the 1 CR2032, I can use it to walk around indoors, once my eyes get adjusted to the dark for a minute or so. At full power it will light up a normal size room. At full power it only draws 6-7ma, so batteries last a long time. At low, it might be Ok for astronomy. With a RED led, it would probably be better? (Guess it depends who you ask !) For me, the green on low does not seem to affect night vision for reading or looking around a dark home.

I just ordered some 700nm "DEEP RED" leds. And will replace the green led, with that one. (Need to pull out and solder on the new led). Beause they produce less lumens, I expect that low, or even medium may be Ok for Astronomy. (But will use up batteries a bit faster. )

I also ordered a Photon Freedom to play around with. It has a continuously adjustable brightness, with a low that is lower than the Photon 3's... It's a green one, and again, replacing the 2 CR2016 batteries with one CR2032 gives plenty of light for indoor use. Even though it's Green LED is more efficient (brighter on high) than my old green photon 3; At it's lowest setting it is a lot dimmer than the photon 3 on low. The Photon Freedom with a Green LED will have a battery life of at least 32 hrs on high. (And longer on lower and still useful PWM settings). (32hrs = 230mah/7ma) This will be my Emergency EDC/Mini-Survival kit. With a RED Led, expect 8 hrs of battery life as the led pulls 4 X the ma At full power.

I may try out one of the 700nm led's in the Photon Freedom. Those LED's can be replaced without soldering...

Another recommendation I have, is to roughen the surface of the LED's with 600 grit "wet or dry" silicon carbide sandpaper. You only need about 1 inch square and about 1 minute to roughen up the surface of the LED. This produces a much smoother beam, that is better for area lighting, and for close up reading. (No shadows or streaks).. It also reduces beam "throw", but that's not what I use microlights for... (There are "diffused" LED's available, but the selection is quite limited in beam angle, and color/nm.)

These can be used as a headlamp either using the clip attachment that comes with the photon freedom; OR by using sitck-on Velcro "Dots". One piece goes on the back of the microlight, and the other on your hat's brim, or eyeglasses, etc...

 

[Blue72]

@dd61999 - it sounds like you are looking for a light for a different purpose, not astronomy, since you mention "in a outdoor environment"....

I use use white light for astronomy as well. As long as the light is dim enough, you can still maintain scotopic vision

 

[survivaledc]

If you can find one, the h502r by zebralight is perfect for what you are looking for.

 

[JAS]

Searching For Very Low Brightness, Red LED Headlamp For Astronomy

A Streamlight ClipMate USB would work. I clip mine to my baseball cap and it works very well for me.

http://www.streamlight.com/en-us/product/product.html?pid=298

Red LED preserves night vision:

Red LED – High:0 .5 lumens; 9 candela; runs 16 hours
Red LED – Low: 0.2 lumens; 3 candela; runs 65 hours

 

[SemiMan]

That wavelength red does nothing to preserve night vision. Better with the same output in white

 

[Nev]

If you can find one, the h502r by zebralight is perfect for what you are looking for.

Zebralights now does a darker red ,they call it photo red , would that be better?

 

[eh4]

http://midopt.com/filters/bp660/

You'll hear that red doesn't preserve night vision, or that it does, but after hearing contradictory information experiment for yourself.
With red light I can more easily transition between darkness and illumination, can see more detail in my center of focus, and don't feel eyestrain.
Dim, warm white is fine too, and that's what I use typically, but it feels and performs differently than red.
The red light that I have is an old CMG Infinity.