Mostly a question for hunters, but I know many others on here favor a red light now an again: are the xp-e2 620nm and xp-e (if you want to go 660nm red, my preference) still top of the heap in the market? Generally speaking, lets say you wanted to build a basic C8 and a basic UF-t20 with a single emitter. Is the xp-e or xp-e2 depending on your color preference still the best there is, without forking over the cash for a red SST-90 
. Anything in the same general price range that competes with the red Crees? How about the oslon ssl 80? Does any other manufacturer have a better option for hobbyist light builds? The only difference I see in the oslon ssl 80 is the tighter 80 degree viewing angle and smaller emitter. Anyone build a non-cree red light that they like better? So far I have a several small zoomies, C8s, and a t20 with red leds, some with buck drivers, some with 7135s. Anybody using different brands for their red leds now adays?
It looks like Cree is finally making a photo red 660nm Xp-E2. Wonder where/when its available.
Other options include the Nichia NCSR219B (fits XP boards) and NCSRE17A, both of which are 620nm. The Luminus SST-10 and Samsung LH351H come in both 620nm and 660nm and fit XP boards.
Arrow, which has free shipping to most parts of the world, and free overnight to the US (yes, even if youāre buying a single $2 LED) has the 660nm LH351H
Thanks! without any output tests from the gurus here, any opinion on which led produces the most output?
The LH351H and XP-E2 should be pretty close.
I did a test once on the red 630nm 219B V1 (never posted it), and it performed well but with slightly less output than the red XP-E2 (625nm).
As far as I know, you can only get them from Cutter at this point of time. Depending on where you are you need to expect quite some shipping cost (approx. $ 10-15).
660 nm from my list:
Nothing really new for deep red. The max power in many datasheets is similar. Very few have been tested here to their limits.
Oslon SSL80 (80Ā°) and SST-10-DR 90Ā° (1 mmĀ² die) could be good for aspheric zooms.
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BTW I got one XP-E HE Photo Red on a 20 mm board from eBay. Have not verified it yet.
Cutter had these red leds in stock in Feb this year.
Can someone explain the difference between ānormalā red and deep red? Iām a bit confused.
620nm versus 660nm. Deep red is a longer wavelength - farther from orange. Thereās also 720nm āfar redā (near-infrared).
So 660nm. deep red is better because itās less orange?
There is no better. The deep red looks less orange next to a 625nm led, it is also about 4 times less visible (you need 4 times the optical power to achieve the same brightness).
Not too exact, but think like this:
typical 620-630nm red is just like something 80-ish CRI red - which are most common in bicycle tail lights
deep reds with 660nm is like getting red in 95 (or above) CRI
Without comparing typical red to deep red, the previous one will look still red, but when you see the deep red, then that will be āTHEā red, and the typical red looks rather like an orange-ish red.
But as djozz says, the human vision is less sensitive to deep red (but even for 730nm far red, most peopleās eye gets triggered a bit, and for even 780nm near infra red, people can expect barely visible light - but I guess, staring into that could be harmful, as there is no good sense of ātoo muchā light entering, which would trigger the pupilās diameter decrease).
For visual use, the āwhiteā LEDs usually donāt go much past 660nm, because then, it would be necessary to convert much light to reds, which we just barely pick up, then overall efficiency would suffer.
Thereās 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:
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 youāre 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.
Hereās 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-E2ās are capable of significantly higher output. On the other hand, if throw isnāt needed, Clemence can mount four of them in a close-packed āquadtrixā 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 donāt 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 āNEW Product Release: Latest Version of the Cree Photo Red 660nm, now in XPG-3. This is a preorder, stock available late May 2019ā
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.