Seoul vs Cree

Which one is better? What is their difference?

I don't think better is quite the right word. They are different, and suitable for slightly different things.

Cree's usually need a different reflector. A seoul can use the same reflector as a Luxeon Led. The cree seems to handle heat a bit better. A seoul is positive at the base if you use a bare emitter. My cree lights usually have a bit better throw and a tighter hot spot...however, I like the broad spot that blends well into the spill of my Seoul lights for closer work. Either will work fine- depends on what you want to accomplish.

my main concern against Seoul (thermal barrier damaging the led in short time because of having to isolate the positive slug) has gone lost with learning that anodized aluminium is not conductive.
So using such a plate as heatsink, one can mount the emitters just like the Cree ...

Thus the main difference is that the Seoul is cheaper.
Cree needs more expensive reflectors to give good results, Seoul work with the cheap IMS.

yellow said:

Thus the main difference is that the Seoul is cheaper.

Click to expand...

Is it? P4 vs P4 I've seen Cree prices a dollar or two less than Seoul. Cree Q4 on the other hand is "just a bit" more expensive than SSC P4.

I meant "ready to use", thought all my type showed that, sorry did not mention at all

emitter + reflector (which is 15,-- for a good Cree one)

yellow said:

emitter + reflector (which is 15,-- for a good Cree one)

Click to expand...

Ow. I think I'll stick with optics. 90% efficiency is OK for me.

no way 90 % imho (there is light behind the optic and this is lost, as I think)
and with the optics You loose throw and usually spill as well.
Even if they were totally identical in output, I just hate to know that there is light around the base of the emitter and inside the light housing with an optic, "behind" it.

Try a 19 mm once and You are lost (thats how I was turned to the reflectors)

2 examples:
1st: the light that extends this "super effective" Tiros optic of Inova from the side and at rear. With a reflector the tongs and wires would lie in complete dark
2nd: a pic of two Cree wired in series (= same current). One with the cree 8 deg. optic and the other with a McR-XR 19 mm. Nearly the same focusing but the optic clearly looses
(the pic does not show the difference in spill, the optic just have none)

yellow said:

With a reflector the tongs and wires would lie in complete dark

Click to expand...

You know, that's mainly 'cause reflectors are opaque.

The second photo I've seen before (great comparison BTW) but the Cree spec sheet says their own optic is 8°. Is the optic providing the dot in the photo some other brand, just fitted onto a Cree?

If you'll refer back to my first post is this thread you'll note I didn't think "better" was really a suitable word for a blanket comparison. Like Macs and PCs, both Crees and SSCs, and also optics and reflectors are suited for slightly different activities, both for their actual performance, and for their cost and availability. How about we aim at that sort of info?

:grouphug:

For example, the optic/reflector performance photo shows that for throw where cost isn't a concern this particular reflector outperforms that particular optic. I'd also like to know what is spill/flood like for the same setup and what are best prices for each?

BTW, I've used the 8° Cree optic and saying there's no spill strikes me as being disingenuous, if my understanding of spill is correct (that it's what comes directly out the front of a reflector setup without being reflected off the reflector) since all the light coming from the front of an optic has gone through the optic, and so technically cannot be spill. The 8° optic is certainly not all spot though; far from it.

As of now, Crees are best suited for optics (narrow beam angle), Seoul's are best for reflectors (wide beam angle). Between the two, I prefer the Crees. Generally, for lights with the same apparent tint/color temperature, I find that the Cree has slightly better color rendering. Likewise, I prefer the beam patterns provided by optics, than those with reflectors, as well.

My biggest gripe with current LEDs and reflectors is the bright spill -- this spill represents direct line of sight to a bright point-source, which means bright glare off of glass, or anything shiny. When using light around other people, keeping the glare out of their eyes can be more of a challenge.

optics, will generally have more of a gradual taper from the hotspot to the spill, causing it to be softer and less irritating. That means when it comes to floody lights, I will generally prefer optics, although I have had some good results using reflector-based lights with light-diffusing UCLs. (some light is lost due to internal secondary reflections, but the end product is nicer for working up close).

When it comes to all-out throwy lights, I find I've been getting better results with aspheric lenses than I have with reflectors, anyway. Those are even less efficient at toal lumen extraction, even using reflective tape around the sides, but they are more efficient than reflectors if the goal is actually getting the lumens onto a target. consider the following photos:



Also, between the two, the reflectors and optics available to consumers are both quite bad -- only extracting 70% of the lumens from a flashlight, at best, is atrocious in my opinion. Considering that those are the results with anti-reflective coated, 99% transmissive glass lenses isntalled, that implies that reflector surfaces themslevs are actually LESS efficient than 70%! Optics are not much better with all the losses to the sides, although generally, with most optics based lights I've been able to greatly improve the output by lining the spaces inside the light behind and around the optic with reflective tape -- that shows poor design on the part of the flashlight maker IMO.

Anyway, I believe that if someone were to make a truly good optic -- that is, with anti-reflective coatings on the entry and exit interfaces, and high-reflective coatings along the edges, much higher efficiencies would be possible, along with the fact that ALL the light can be controlled, could lead to some good results. However, there is nothing like that available, from what I understand. Likewise, higher-efficiency reflector coatings than what we're apparently seeing are certainly possible as well, such as those used in telescopes.

I would be interested in seeing what sort of results might be achievable using some sort of hybrid system -- such as an optic with a reflector to control any light that "leaks" from the optic. Given the cheap parts that we have to work with (no exotic coatings etc.) that might yield the best results. Another option would be to use an aspheric lens, along with an elliptical reflector with the proper focal lengths (one at the emitter, one at the lens interface) similar to how projector headlights work. Something like that with an HID or incan could produce amazing throw.

that "6 deg" is my fault, must check if I still have the original pic and change the 6 to the 8.
Anyway, it were 2 Crees from the same batch, the one with the original Cree optic and the other with the reflector and wired in series to run on same current.

I'm not sure how to explain what I mean with "no spill". :thinking:
Sure, the optic makes spill also, but when looking at it (I was not able to get this in a pic), the optic illuminates an area of full 180 degrees around the emitter, shining through that white optic holder (makes the light creamy). Bright enough to read a newspaper, but not very bright.
With a reflector one has the main dot and a less bright 2nd illumination ring around it.

maybe easier with these pics:
with the optic (here with the correct "8" deg ), the spill is much weaker and spread over a considerably wider area. Even in the 1st pic, the whole wall is illuminated already.
with the 19 mm the 2nd ring (spill part) is considerably brighter and the wall starts to shine into at the 3rd pic, when the spill illuminates it
(pls. ignore the vertical black stripes, come from the rubber band holding the reflector in place temporarily)
degree of focusing seems very identical to me, both about these 8 deg.




PS: these pics are no brightness comparison - were made to show the different focusing - Cam was on auto.

2xTrinity said:

Optics are not much better with all the losses to the sides, although generally, with most optics based lights I've been able to greatly improve the output by lining the spaces inside the light behind and around the optic with reflective tape -- that shows poor design on the part of the flashlight maker IMO.

Anyway, I believe that if someone were to make a truly good optic -- that is, with anti-reflective coatings on the entry and exit interfaces, and high-reflective coatings along the edges, much higher efficiencies would be possible, along with the fact that ALL the light can be controlled, could lead to some good results. However, there is nothing like that available, from what I understand. Likewise, higher-efficiency reflector coatings than what we're apparently seeing are certainly possible as well, such as those used in telescopes.

I would be interested in seeing what sort of results might be achievable using some sort of hybrid system -- such as an optic with a reflector to control any light that "leaks" from the optic. Given the cheap parts that we have to work with (no exotic coatings etc.) that might yield the best results. Another option would be to use an aspheric lens, along with an elliptical reflector with the proper focal lengths (one at the emitter, one at the lens interface) similar to how projector headlights work. Something like that with an HID or incan could produce amazing throw.

Click to expand...

I'm not sure what kind of problems optic producers are having. They should easily be able to create an optic where the refractive index difference between the optic and air should be high enough that any light from the emitter would be at an angle greater then the critical angle and result in total internal reflection. I did work with lasers in the past and we used glass or polycarbonate prisms instead of mirrors to bounce lasers because they were more efficient. Total internal reflection should mean zero loss, but if you have to wrap reflective tape around the optic, then they are not able to correctly create angles of light greater then the critical angle for whatever reason. Since they can't make the perfect optic, the reflective surface around the sides of the optic should help - I can't imagine why no one is doing it yet.

When people talk of wrapping reflective tape around the optic, they mean around the inside of the optic holder, right? Surely putting anything (even a fingerprint?) on the outside surface of the optic itself would affect the TIR?

TorchBoy said:

When people talk of wrapping reflective tape around the optic, they mean around the inside of the optic holder, right? Surely putting anything (even a fingerprint?) on the outside surface of the optic itself would affect the TIR?

Click to expand...

Yes, inside the optic holder - since their obviously not creating total internal reflections inside the optic.

How is Seoul development proceeding in comparison to Cree?

I just noticed that Cree has the Q4 now while I haven't seen anything new from Seoul.

If you use a deep reflector with the Cree it throws really well and still has a good side spill beam.

I have a mag powered by a Flupic and a Seoul P4 and a smaller 4 1/2 inch light with a deep reflector powered by a piglet at 850mA and a Q2 XRE. The smaller light has a tighter spot and puts out more light than the P4.

For me, I will stick with the Cree LEDs over the SSC. IMHO, I can use the Cree with optics and the correct reflector with great results.

When people talk of wrapping reflective tape around the optic, they mean around the inside of the optic holder, right? Surely putting anything (even a fingerprint?) on the outside surface of the optic itself would affect the TIR?

Click to expand...

That's correct, I'm not putting anything against the surface of the optic, just in the optic holder, or walls of the light if there is no holder. I believe the light that leaks is probably happening because the interfaces where the light enters, and exits the light are not anti-reflective coated, these secondary reflections then may not be at the correct angle to internally reflect, and then pass through. In the case of some Cree optics, I think things like the "yellow ring" artifact (reflection off of the aluminum that holds the glass dome down) may leak through to some extent as well. In the case of a reflector based light, light that reflects off of the glass window will mostly bounce back off of the reflector again. Losses due to this should only be 10% or less, but even still, IMO that is good reason to AR coat the interfaces.

Best hong kong has a nice $1.00 reflector that works well with the Seoul Led. I used a number of them. WIth and without a lip. Don't use their lens...it's not for the cree that we use. I tired one of the DX lenses for a cree and it works pretty darn good. I got the .75 inch one with the holder ( 10 pack ).http://www.besthongkong.com/product_info.php?cPath=19_22&products_id=235

Hi.

This may sound insane. However, has any one ever tried to use both optics and reflectors together? (well fitting i mean).

I've had some interesting results with just the old used stuff i have hanging around.

TTFN