xre vs xml for throw?

[gcbryan]

Peter, if you take the larger reflectors that you are talking about for the larger emitters that give the throw you refer to and put a XR-E in that same diameter reflector the XR-E will throw further than the larger emitters.

You don't have to talk about putting an XM-L into a too small reflector. Put it in a properly sized reflector but just put a XR-E in that same reflector...and you will get more throw.

 

[peterharvey73]

If a bigger emitter like an XM-L versus a smaller emitter like an XR-E R2, are both placed in the same size reflectors, then certainly the XR-E out-throws the XM-L.

Btw PCC, very good to learn that the smaller XR-E emitter can be overdriven harder than their maximum specifications over the bigger emitters because they have a larger footprint beneath the die.

However, in practice:
1) How do we account for the fact that the SR-90, RRT-3, M2S, M3C4, M3X, and Catapult V3 are all SST-90, SST-50 and XM-L emitters?
Surely the engineers couldn't have gone wrong and chosen the wrong emitter?

2) Imagine what would happen if we placed the XR-E R2 emitter into these six big lights?
How would the XR-E R2's beam compare to the current six listed above?
Would it really throw further than these six big lights?

Presently I don't understand exactly why the XR-E R2's aren't used in those six big lights.
I am curious. I'd have to talk to an engineer.
However, I have a hunch the XR-E is not all that perfect, and there must be some shortcomings to the XR-E R2 - the market is flooded with the bigger emitters - and look at the light and throw the bigger emitters produce, esp in the bigger lights?

 

[PCC]

Why don't they use the XR-E in those lights? Because the XR-E is yesterday's news and lumens sell lights. No one but a true flashaholic would buy a 225 lumen super thrower when you can pay slightly more for that monster 600+ lumen light. The XR-E was supposed to have been replaced with the XP-E. It doesn't help that it gives a ringy beam when used with a smooth reflector. No manufacturer will sell a light that has an LED that is overdriven significantly so anything that I have said about overdriving these LEDs is moot when it comes to a flashlight that not a custom job.

 

[peterharvey73]

Actually, I'm beginning to wonder if the XR-E can NOT out-throw the bigger emitters from the SR-90, RRT-3, Et M3C4, Catapult V3 XM-L because throw is dependent, not just on the emitter to reflector size ratio, but also on the total lumen output?
In other words, the greater the total lumen output, the greater the throw.
Thus, a 200 lumen XR-E will throw further than a 100 lumen XR-E, given all else is the same.

So an XR-E is handicapped by it's limited output of only say 200+ lumens.
On the otherhand, an XM-L can total output 1000 lumens!

Now, when that big XM-L powerful emitter is placed in say a small reflector like a Zebralight SC600, we get heavy flooding with poor throw, because the emitter has increased greatly in size, but the head/reflector size is the same compact size at some 30 mm in diameter.
However, when that big powerful XM-L emitter is placed in say a big flashlight & reflector like the Et M3C4 or a Catapult V3 etc, bang!
They both throw a long long way.

Does this explain why XM-L's, SST-50's and SST-90's are used in the bigger lights?
The bigger emitters have more total lumens too - and that helps greatly in the overall throw...

 

[gcbryan]

In part it's because there are already larger "turbo head" models using the XR-E or XP-E. In part it's because some people want a useful light that has a good amount of throw rather than having the ultimate thrower when the beam of light it puts on the target is so small as to not be useful in many application.

A laser is the ultimate thrower but it's of limited use. If someone wanted a thrower for search and rescue it might be more useful to have a lot of light in a larger area at 600 feet rather than a tiny spot at 800 feet.

Ultimate throw isn't a goal for most useful applications. Once a light can throw as far as we can see then the goal is to put more light at that distance.

There's nothing wrong with the XR-E. That's not why the engineers are using XM-L instead. XM-L is capable of taking more current than XR-E and therefore capable of putting out more light.

 

[gcbryan]

Actually, I'm beginning to wonder if the XR-E can NOT out-throw the bigger emitters from the SR-90, RRT-3, Et M3C4, Catapult V3 XM-L because throw is dependent, not just on the emitter to reflector size ratio, but also on the total lumen output?
In other words, the greater the total lumen output, the greater the throw.
Thus, a 200 lumen XR-E will throw further than a 100 lumen XR-E, given all else is the same.

So an XR-E is handicapped by it's limited output of only say 200+ lumens.
On the otherhand, an XM-L can total output 1000 lumens!

Now, when that big XM-L powerful emitter is placed in say a small reflector like a Zebralight SC600, we get heavy flooding with poor throw, because the emitter has increased greatly in size, but the head/reflector size is the same compact size at some 30 mm in diameter.
However, when that big powerful XM-L emitter is placed in say a big flashlight & reflector like the Et M3C4 or a Catapult V3 etc, bang!
They both throw a long long way.

Does this explain why XM-L's, SST-50's and SST-90's are used in the bigger lights?
The bigger emitters have more total lumens too - and that helps greatly in the overall throw...

You are just not understanding throw. Surface brightness and reflector diameter is all throw is. Forget about lumens. That is taken care of in the measurement for surface brightness in effect. Surface brightness is the lument output a max spec divided by the emitter size. XR-E and XP-E currently win that race.

 

[peterharvey73]

So what you are saying is that, if we hypothetically put an XR-E into an SR-90, Eagletac M3C4 or Thrunite Catapult etc, the XR-E emitter will actually out-throw the original bigger emitters?
However the manufacturers have deliberately not used the XR-E emitter due to insufficient total volume/quantity of light, esp a more practical huge/wider hotspot, and more practical lateral flooding?

The only reason why I ask, is because Selfbuit's data says:
1) A Jb RRT-2 XR-E R2 throws something like 216 meters to 0.25 lux.
2) An Eagletac M3C4 XM-L throws 394 meters to 0.25 lux.
3) A Catapult V3 XM-L throws 402 meters to 0.25 lux.
4) A SR-90 SST-90 throws 634 meters to 0.25 lux.
Selfbuilt's data says that the bigger more powerful emitters are throwing much further?

 

[gcbryan]

So what you are saying is that, if we hypothetically put an XR-E into an SR-90, Eagletac M3C4 or Thrunite Catapult etc, the XR-E emitter will actually out-throw the original bigger emitters?
However the manufacturers have deliberately not used the XR-E emitter due to insufficient total volume/quantity of light, esp a more practical huge/wider hotspot, and more practical lateral flooding?

The only reason why I ask, is because Selfbuit's data says:
1) A Jb RRT-2 XR-E R2 throws something like 212 meters to 0.25 lux.
2) An Eagletac M3C4 XM-L throws 394 meters to 0.25 lux.
3) A Catapult V3 XM-L throws 402 meters to 0.25 lux.
4) A SR-90 SST-90 throws 634 meters to 0.25 lux.
Selfbuilt's data says that the bigger more powerful emitters are throwing much further?

No, his data says that manufacturers are putting XR-E's in smaller lights than they are putting XM-L's. They don't need the same current to drive them so they can use smaller batteries and therefore be smaller.

A XM-L to be fully driven needs 3A and therefore to have reasonable runtime more and bigger batteries...a bigger light. The XM-L is a bigger emitter and to throw at all needs a big diameter reflector.

So when you are picking your data you aren't really talking about XM-L and XR-E...you are talking about what Jetbeam did in a particular model or whoever.

The answer to your first question is yes. The XR-E will throw further than the bigger emitter. The size of the emitter has to do with how many lumens it can put out not lux.

It might be like saying that pound for pound a 12 year old girl is stronger than you are. I climb outdoors but also at a climbing gym. You and I are stronger than a 12 year old girl but I see kids that may be able to climb better than we can until puberty hits. The ratio of her arm strength to weight is higher than ours. It's not that she is strong. She just doesn't weigh anything.

The larger emitters increased lumen output over the XR-E but didn't quite catch up with their size. Their size went up 100% lets say but their lumen increase only went up by 75%. Proportionately the XR-E is still "stronger"

 

[peterharvey73]

Your analogy of the strong 12 yo girl is a good one.
Perhaps that helps to explain why the XR-E has the most surface brightness.

Yet say the SR-90 has 634 meter of throw on Selfbuilt's tests.
Catapult V3 XM-L throws 402 meters to 0.25 lux.
An Eagletac M3C4 XM-L throws 394 meters to 0.25 lux.
By comparison, a Jb RRT-2 XR-E R2 throws something like 216 meters to 0.25 lux.

 

[MikeAusC]

Your theory is valid for de-domed LEDs with diverging or parallel beam reflectors. Don't forget that you can converge a beam too.

And once you add the micro-lens you're screwing the whole thing pretty much.

Nap.

Exactly - the optics used in an XR-E work differently to all later CREEs - the XR-E focusses its light much more tightly at 90 half brightness width. All later CREEs use lenses that give 120 deg half brightness width.

So unless you're comparing de-domed LEDs, there's no point talking about chip size - you have to compare APPARENT chip size - i.e. how big it looks through the attached lens.

 

[jorn]

The deft has passed 400 000 lux with a xr-e.
http://www.candlepowerforums.com/vb...rst-LED-flashlight-to-break-the-400K-Lux-mark
A huge xr-e thrower with a laserbeam and a carrystrap wont sell very well. So no one want's to risk money on making one. That dont make the xm-l emitter a better trower. It's a better seller in big lights.

 

[Napalm]

A huge xr-e thrower with a laserbeam and a carrystrap wont sell very well. So no one want's to risk money on making one. That dont make the xm-l emitter a better trower. It's a better seller in big lights.

This is mostly an academic experiment. Yes, it's easier to focus a smaller light source with simple optics, but coin sized hotspots with no spill don't have many practical applications. And when you start spreading the beam to an useful size, it's the XM-L that delivers.

Nap.

 

[jorn]

This is mostly an academic experiment. Yes, it's easier to focus a smaller light source with simple optics, but coin sized hotspots with no spill don't have many practical applications. And when you start spreading the beam to an useful size, it's the XM-L that delivers.

Nap.

Yes the xm-l makes a more useful beam with a huge reflector, but it wont be making a more throwy beam than a xr-e. We are discussing what LED will give most throw of the xr-e vs xm-l, not what got the most useful and allaround beampattern.

 

[Napalm]

We are discussing what LED will give most throw of the xr-e vs xm-l, not what got the most useful and allaround beampattern.

I would be more interested in discussing what LED will give most USEFUL throw.

Nap.

 

[gcbryan]

I would be more interested in discussing what LED will give most USEFUL throw.

Nap.

There really is nothing to discuss and therefore no real point to this thread :)

XR-E has more throw...nothing to discuss.
XM-L is more useful in most applications where more light on the target/subject is needed.

The middle ground is when you want a directed beam in a small easy to carry light...XR-E wins here as well.

Very little to discuss however. If you want to light up the distance get a large diameter XM-L fully driven. If you want a small hand carry pointer light to identify critters on your nature walk get a XR-E.

 

[peterharvey73]

When u calculate the surface brightness, I guess the XR-E does have an advantage.
Olight SR-90, SST-90, 2200 lumens divided by 9 sq mm [3mm x 3mm] = 244 lumens per sq mm
Jetbeam RRT-3, SST-50, 1200 lumens divided by 5 sq mm [2.25mm x 2.25mm] = 240 lumens per sq mm
Eagletac M3C4, XM-L, 1000 lumens divided by 4 sq mm [2mm x 2mm] = 250 lumens per sq mm

An old Jb RRT-2 XR-E R2 @ 240 lumens divided by 1 sq mm [1mm x 1mm] = 240 lumens per sq mm.
However, this 240 lumens maybe quite tricky, because the three above may be all driven to their maximum amperage @ 9, 5, and 3 amps respectively???
The RRT-2 is unlikely to be driven to it's maximum amperage? [This is probably what I missed]?
At it's maximum amperage, the XR-E may be delivering some 300 lumens per sq mm???
Thus, if the XR-E was driven to it's max amperage, and was placed in the same 100mm reflector as an Olight SR-90, the XR-E may indeed out-throw the XM-L, SST-50 & SST-90.
Like MikeAusC says, the XR-E has beam emittance angles which at 90 degrees, is narrower too than the XP-G & XM-L's 125 degrees, and the MC-E's 110 degrees.

So for out-right throw, the XR-E does indeed seem to win.
However, for practical purposes, the bigger emitters are used because they throw far enough for the human eye to see, yet their hotspots are significantly larger, and their lateral spills are significantly brighter...

Special thanks to goinggear's useful youtube beam throw videos [above], and Selfbuilt's throw data [above], to understanding the science behind how emitters and throw work.
Unfortunately, Selfbuilt did not measure throw to 0.25 lux in the old days of the XR-E R2 and XP-G R5; he only recently started to measure throw roughly when XM-L's came out...

 

[PCC]

When u calculate the surface brightness, I guess the XR-E does have an advantage.
Olight SR-90, SST-90, 2200 lumens divided by 9 sq mm [3mm x 3mm] = 244 lumens per sq mm
Jetbeam RRT-3, SST-50, 1200 lumens divided by 5 sq mm [2.25mm x 2.25mm] = 240 lumens per sq mm
Eagletac M3C4, XM-L, 1000 lumens divided by 4 sq mm [2mm x 2mm] = 250 lumens per sq mm

An old Jb RRT-2 XR-E R2 @ 240 lumens divided by 1 sq mm [1mm x 1mm] = 240 lumens per sq mm.
However, this 240 lumens maybe quite tricky, because the three above may be all driven to their maximum amperage @ 9, 5, and 3 amps respectively???
The RRT-2 is unlikely to be driven to it's maximum amperage? [This is probably what I missed]?
At it's maximum amperage, the XR-E may be delivering some 300 lumens per sq mm???
Thus, if the XR-E was driven to it's max amperage, and was placed in the same 100mm reflector as an Olight SR-90, the XR-E may indeed out-throw the XM-L, SST-50 & SST-90.
Like MikeAusC says, the XR-E has beam emittance angles which are narrower too.

You're comparing apples to oranges here: the ratings for the SST-90, SST-50, and XM-L are manufacturer's maximum ratings while the rating for the XR-E is a manufacturer's (probably inflated) OTF rating. The XR-E R2 has been tested to produce anywhere from 300 to 310 lumens at 1.2A, the manufacturer's maximum current rating. Keep in mind that Cree did a running change to their XR-E emitters at some point and actually reduced the die size from 1mm^2 (EZ1000) to 0.9mm^2 (EZ900 - someone correct me here if I'm wrong, this is from memory). The above tests were performed on EZ1000 die emitters and the slightly smaller EZ900 emitters can't quite take the same amount of abuse as the slightly larger EZ1000s. Since Cree kept the bin rating for the emitters the same this means that, at the maximum drive current, the newer EZ900 die XR-Es are making even more lumens per square millimeter than the older versions by roughly 10%. What's the result? Roughly 300 lumens per sq mm for the EZ1000 XR-Es that can be overdriven substantially (to about 400 lumens at 2A) or 330 lumens for the newer EZ900s.

BTW, an XP-E R2 was tested as well and it made 270 lumens at 1.2A and only 327 lumens at 2A. I wonder how well the XP-E R3 compares. Both of these LEDs are using EZ900 dies.

Here's my source for this information.

 

[gcbryan]

Also keep in mind if you are getting throw with an aspheric that there is another advantage (over a reflector) with the XR-E. Its beam angle of 90 degrees means that more of the emitted beam is hitting the aspheric than the reflector.

Something like an XP-G iis more efficient in a reflector since more of its beam is hitting the reflector. That's not to say that it throws further but just that there is less advantage to using a XP-G in an aspheric.

 

[wamcneil]

Yes, but what if it was an African swallow AND it had a tiny jetpack? Then perhaps it could be explained...
Seriously though... from my noob perspective, the XM-L is great in a P60 or bigger reflector, but for smaller reflectors, and especially single cell lights, is there any point in the XM-L? To me, XP-G and even earlier emitters may be just as good in smaller lights if you want any throw at all.

 

[Napalm]

I suggest that the throw maniacs replace their car headlights with a pair of nicely focused XR-Es and then post here how it worked for them.

Nap. :p