Red Leds: Is cree still the best option for flashlights?

There’s also Luxeon CZ, Z & Rebel in 660nm

XP-E deep red 670nm.

XP-E2 red 620nm

I focus on LEDs for flashlights. If they are too small or if I do not find any DTP MCPCB I do not care.
Luxeon CZ is just a C with less power and Z has a weird footprint without the history of the Rebel.
Rebel is in the table.

Djozz is right, the deeper red that a lot of manufacturers have various names for like "photo red" or whatever oslon calls their different nm rated lights, are only really noticeable to a novice like me is when white wall shining two together. Put a 620nm xp-e2 next to a "photo red" 660nm xp-e, and the 620nm appears orange. But, after using the deeper reds, the tint is noticeably more pleasant than the 620nm from a tint-stob (pleasant to the eye) perspective.

But, there's also a good reason to use them since a lot of red lights are for hunting. I've never gone for the "far red" above 660nm because too much of it is out of the visible human spectrum. The higher nm you go, the less output you can perceive, so the photo red lights won't ever have as much visible output. Unless you're using digital night vision, which is another story.

Considering red led's generally have low visible output anyway, I don't notice much difference in functionality between a 620nm xp-e2 and a photo red xp-e. However, tint-snobbery aside, there is a basis for the distinction if you want to use the light for hunting. While a lot of that light is still in the human range, it is even more removed from the visible spectrum of a lot of animals that are hunted at night (feral hogs, predators, etc). Not really scientific, but here's a brief explanation on why I like the higher range reds in addition to the subjectively "nicer" tint:

https://outriggeroutdoors.com/blogs/rigged-up/the-science-behind-choosing-a-red-or-green-light-for-night-hunting

In short, I have a C8 with a de-domed xp-e2 620nm normal red, and a xp-e photo red, both around 2A driven. I notice no difference in range or real usefulness other than the photo red looks red and the 620nm is orange side by side. If it makes a difference to the wildlife you're trying to spot, so much the better. I just know I like the appearance of the deeper red once I got used to it, and the added bonus is being less visible at night to animals. Just be careful not to shine light above 660nm near your's or someone else's face. With infrareds, just because it isn't visible doesn't mean it isn't damaging your retinas.

This is probably not what you’re looking for, but since it is interesting and available, it seemed worth mentioning:

Clemence has recently started selling Nichia E17A phosphor converted red emitters. While he used to offer a modified Jetbeam Jet-u with them, I believe now you can just order the emitters, optionally presoldered onto a compatible MCPCB.

Because it is phosphor converted, it has a wider spectrum than a typical red LED. These means more extension into the deep reds, but also into the red-orange. That could potentially aid object discrimination, but also could mean more likely to be perceived by animals.

Here’s a comparison to the XP-E2

Red XP-E2* Red E17A
Peak 625nm 645nm
Spectral FWHM ~25nm ~100nm
Max Rated Current 1000mA 700mA
350mA Output 84 lumens 31 lumens

Obviously, single XP-E2’s are capable of significantly higher output. On the other hand, if throw isn’t needed, Clemence can mount four of them in a close-packed “quadtrix” format. I expect that would work decently well with a Convoy S2+ and one of the TIR optics that the Convoy Ali Express store has available. I don’t know how the beam shape would be if used in a smooth reflector like in a C8.

/* Edit - The photo red XP-E2 is closer to the E17A in peak wavelength, but Cree only gives the output for the photo red in mW of optical power, not lumens. If this table is accurate, then the 650nm photo red XP-E2 should produce 43 lumens at 350mA

Cutter au has a “NEW Product Release: Latest Version of the Cree Photo Red 660nm, now in XPG-3. This is a preorder, stock available late May 2019”

link to product page: https://www.cutter.com.au/product/xpgdpr-l1-0000-00g01/

According to the official spreadsheet the red XPG-3 can handle 1.5A max and the XP-E2 1.0A.

Djozz measured the XP-E2 can handle a bit more than ~2.5A I wonder how much the XPG-3 could get max and how it compares to the XP-E2.

According to the spreadsheet the Photo Red XP-G3 has a typical wavelength of 645nm and peak wavelength of 670nm. The XP-E2 only has a peak wavelength of 650nm listed. I’m confused again, which one is better in terms of tint? = more red.

Define: more red

The XP-G3 datasheet says:
Peak Wavelength Minimum: 650nm
Peak Wavelength Maximum: 670nm

Dominant Wavelength: 645nm

The range of peaks is listed, as I understand, because there can be variation between batches.

Peak is where wavelength with the highest intensity. I wasn’t aware dominant wavelength was a separate specification, but from a quick search, I guess the difference is peak is based strictly on spectral power density, but dominant sounds like it is in some manner a perceptual specification. I guess maybe it’s adjusted based on the human eye sensitivity to the wavelength that would appear identical from a true monochromatic source (color LED’s are close to monochromatic, but not quite).

The XP-E2 datasheet does not specify dominant wavelength. The peak wavelength minimum and maximum are the same as the XP-G3.

Both should appear basically the same.

Closer to the deep red wavelengths. The 620nm XP-E2 is indeed a bit orange-ish.

Thanks for the explanation. But XP-G3 has better parameters and should handle a bit more current. Maybe I’ll organise a small groupbuy (approx. 30 leds).

I see. In my perception (everyone differs a bit in how far red they see), at longer wavelenths than 660nm the colour of red does not change anymore and your eyes do get more and more insensitive for it. A good compromise I think is 640nm: looks very red and not orange, and you do not need bucketloads of output (as in: radiometric output) to be able to see something.

Hmm, so if the XP-G3 is slightly less into the far red wavelengths than the XP-E2 it’s actually good.

In my perception and opinion yes, but there is a sort of myth that the higher the wavelength, the better while in fact you are going to see less and less instead of a “redder” colour.
And there’s the hunters who like all sorts of colours for as many reasons as there are colours, but I do not know much about that.

Digi-Key lists 645nm for the XP-G3.
As soon as they will become available at mouser, roughly late july I’ll organise a small groupbuy 30-35 leds from them. Even with import taxes the price should be decent.

From Mouser for G bin of red XP-G3:

"End of Life: Scheduled for obsolescence and will be discontinued by the manufacturer."

Strange.

:+1: good idea, in for 5

Bump to see if anyone has tried one of the new xp-g3’s in photo red. I have enough photo red xp-e2 and xp-e’s, but wanted to see if anyone’s built a light with one yet? Was the group-by was ever organized? I’d be in. Thanks

Darnnit guys - you’re making me want to get teh gear to change out LEDs….

I wonder - would my .mil buddies like an IR FW3a?

How about a C8f Triple with the new red xp-g3’s? That’d be a killer hunting light, and easier to put a remote switch in the tail (I assume). I wonder if the output of the Xp-g3 is much more than a high-binned xp-e2 in red/photo-red. Obviously the xp-e2 throws better and can be de-domed if you wish instead of trying to slice the xp-g3, but hopefully the xp-g3 has a substantial increase in output. Interested to hear when someone gets their hands on one of these to test out.

I have tested the 660nm XP-G3 but have been too lazy to post the result sofar (=on my list). The output is really good, in lumen comparable to the 625nm XP-E2, but consider that your eyes, and the luxmeter, is 4 times less sensitive to 660nm than 625nm. The die is larger though so it is less throwy.