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Led Torches - A Quick 'n' Dirty Guide


fenring
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Hi everyone.

There are always a lot of questions and interest surrounding high performance LED torches on the forum, and sometimes a bit of confusion over terminology, lumen ratings, what makes a good hunting torch and so on.

So I thought it might be handy if someone stuck up a basic guideline about modern LED torches to give forum members an idea of what it’s all about, the terms used and what to look for when choosing an LED torch.

I am by no means an expert on the topic, but I know a bit from my own research and experience over the three or so years I’ve been hunting critters using nothing more than LED torches mounted on a rifle or shotgun.

I suppose for starters a brief glossary of terms would be a good idea:

LED emitter or “chip” – the actual light emitting diode, most often yellow in colour on torches that emit a white coloured light. You will also see red, blue and green ones that emit those colours of light. Emitters are made by a number of companies – the most common being Cree, but you also see a lot of Seol Semi Conductor (Or SSC for short) emitters. In bigger lights you sometimes see Luminus branded emitters, most often the big SST50 or SST90. There are other makers but in torches these three are the most common manufacturers.

LED binning – manufacturers rate the LED’s they produce by how much light they produce at a certain amperage. They are then assigned a code that places them in order of how efficient they are. You will often hear talk of an “R2” or “Q5” LED – these are in fact the same emitter, the Cree XR-E, but different binning – the R2 being the more efficient. With the XP-G you will often hear it called an “R5” in reference to the binning. But the model is XP-G and they are not referring to it correctly. The new XM-L is most often seen in the T6 range.

Driver- an electronic circuit board that sits between the battery and the emitter, that controls current, and multiple modes if the torch has them.

Reflector or optic – the metal or plastic reflector that collimates the light from the emitter and sends it out the front of the torch. Reflectors are either smooth or textured, or sometimes rarely a combination of both. As a general rule, a smooth reflector scatters the light less and projects the beam further. In some torches you will see an optic instead of a reflector – an optic is often made of high quality plastic and fits directly over the LED emitter to capture all the light. It’s basically like a solid funnel that captures the light and emits it out the front of the torch just as a reflector does – an optic can be designed to give any beam pattern that’s desired – from a flood beam to a tight spot. On lights like the LED Lenser P7 and the EDI-T torches you will see what is known as an aspheric lens – this is a thick, domed lens that sits above the emitter and captures all the light – there is no reflector, generally a matte surface around the emitter. These lenses normally come with a movable focusing ring that lets you adjust the focal length and thus how the beam is projected – from a very tight spot often shaped like the square of the emitter, to a broad flood beam.

Recoil LED – an LED torch with the emitter mounted at the lend end of the head, where the LED shines backwards towards the reflector, and the light is then bounced forwards out of the torch. Just like the way a lighthouse works. Typicall, the beam is very tightly focused.

Aspheric lens – a thick convex lens that looks like a fish eye. The idea is that the light from the LED hits the back of the lens and is concentrated into an intense spot as it passes through. Examples of these are found on the popular LED Lenser P7, which is a moveable lens and thus the focus of the beam may be varied by the user. A fixed one such as is available for the Tiablo A9 is locked in place and designed to give the tightest beam possible – the beam is normally is square in shape just like the emitter itself and there is virtually no side spill with this type of setup. It’s all about long range!

Regulated and unregulated torches – many torches have what is known as a regulation circuit built into them. Essentially, this circuit works to feed a constant supply of power to the emitter for as long as the battery can sustain it. So the torch remains at a constant brightness level for a certain period. Some regulated torches will cut out once the circuit detects that the voltage is too low – sometimes you will notice the light warning you by starting to flicker just before this happens. Some will then go to direct drive mode and begin to dim just like an unregulated light. An unregulated or direct drive torch will start to dim, imperceptibly, as soon as it is turned on. So while the light might have 200 lumens with brand new batteries this will slowly fall off to a point where the light is very dull.

Host or torch body – this is the chassis of the torch that holds the battery, the electronics and the lens. You may hear people talk of “P60” hosts – these are torch bodies that take a standard size self contained module called a “P60”. On these lights you can remove the entire driver, emitter, and reflector in one unit and replace it. Examples of P60 hosts are the Solarforce L2, Ultrafire 501B, and Surefire L2. As the LED unit can be replaced, they are entirely user serviceable and you can have several LED units to suit different uses. Different beam patterns, different colours, multiple modes, change lenses, etc.

Forward clicky - a switch that turns on the light with the button partially depressed and then locks into on once it is fully depressed and clicked. This allows "momentary on" by halfway depressing the switch.

Reverse clicky - a switch that must be fully depressed, clicked, and released before the light comes on. Once the light is on, a half-press will turn the light off momentarily and/or change modes once released. It is good for multi-mode lights, but does not allow momentary on

Lumens – a measurement of overall light output.

Emitter lumens – how many lumens are coming out of the actual LED. A bit like horsepower at the flywheel of an engine.

Out the front or OTF lumens – how many lumens are actually coming out of the torch after there are losses through the lens and stray light scattered and lost. Kind of like rear wheel horsepower.

Lux – a measurement of light intensity.

Luminous flux – how much light an emitter produces at a given amperage. The ability of the emitter to make light. Call it horsepower per litre if you like.

Potting or potted – the process whereby the electronic driver circuit is filled with epoxy or similar material to increase resistance to recoil and impact. Can be important on harder recoiling weapons.

Viewing angle- essentially, the angle at which the light is emitted from the LED chip. The lower the viewing angle, the tighter the spread of light emitted.

That covers most of the commonly used terms that people might not be familiar with.

On the topic of LED’s, the emitter is a crucial part of the torch as it not only produces the light but the type of emitter affects how much light a torch can produce and what sort of beam pattern you get out of the business end.

Here’s a quick rundown on the most common emitters you see in torches:

Cree XR-E: a small emitter that can handle up to about 1 amp of power with a luminous flux of 120 lumens at 350mA. The XR-E has a tight viewing angle of 90 degrees meaning it emits a tightly focused beam. This is the emitter most commonly seen in the long range thrower torches. You will often see this emitter simply called a “Cree R2” or “Cree Q5”. Commonly, torches with this are around 200 – 250 lumens.

Cree XP-E : a very small emitter, often seen in mobile phone camera flashes. Capable of handling 1A and with a luminous flux of around 115 lumens at 350mA. Viewing angle is 115 degrees. Not overly common in LED torches compared to the XR-E and XP-G. Most torches with this are 200 lumens or less.

Cree XP-G: also a very small emitter but this one can handle up to about 1.5A. This one is a bit newer than the XR-E and more efficient, with a luminous flux of around 135 lumens at 350mA. This one has a viewing angle of 125 degrees so its emission is not as tightly focused. Very popular in LED torches and often called simply a “Cree R5.” Most torches using this are producing around 250 – 350 lumens.

Cree XM-L: this is a very new emitter, larger than the others and can handle much more power. The XM-L can handle 3A of power and has a luminous flux of around 280 lumens at 700mA. This one has a viewing angle of 125 degrees like the XP-G. The most common binning that you see is the T6. This is a powerful LED, easily producing anywhere from 500 to 1000 lumens.

Cree MCE: another large emitter, actually made up of four smaller chips together under the one dome. This one can actually be had with multiple coloured chips on the one emitter. So a four coloured light all in one, with the different colours able to be selected via the switch. This one can handle up to 700mA with a luminous flux of around 300 lumen at 350mA. The viewing angle is 110 degrees.

Seoul Semiconductor P7 or SSC P7: a larger emitter with high power handling of 2.8A and luminous flux of around 400 lumens at 1400mA. This is a bit like the MCE, in that you can see 4 chips on its surface. The viewing angle of this one is 130 degrees – so quite wide. Often called just a “P7” or “SSC P7.”

Luminus SST50: another larger chip with very high power handling up to 5A. Luminous flux is around 350 lumens at 1.75A. Viewing angle is 100 degrees.

Luminus SST90: you don’t often see these in torches. A large and powerful emitter, 9mm across and capable of putting out over 2200 lumens. This big fella can swallow 9A and has a luminous flux of around 900 lumens at 3.15A and a viewing angle of 100 degrees.

That’s a quick rundown on the commonly used terms and the most common LED emitters. Where there is a lot of confusion is where the output of the torch in lumens is mentioned – the assumption being that more lumens has to be better for a hunting light – right? Wrong. The lumen rating only tells you how much light is claimed to be coming out of the end of the torch – it does not tell you how that light is focused. You can have a 1000 lumen torch that won’t shine past 100 metres by virtue of it being very floody. You can have a 100 lumen torch that shines 150m thanks to it being very tightly focused.

How can you tell if a light is going to throw well? For starters, the type of LED it has will give you a clue. If it has an XR-E (often called just an R2 or Q5 emitter) you are on the way. The next thing to look for is a smooth finished reflector – the deeper and wider the better. The depth and width captures all the emitter lumens and collimates them into a tight beam, and sends them out the front with minimal scatter. An aspheric lens also does the same thing – though poor quality aspheric lenses can cost a bit of efficiency just like a grimy window. A true 200 OTF lumen torch with an XR-E emitter in a smooth, deepish reflector will let you shoot at 150m.

The XP-E and XP-G emitters can also have decent throw if teamed with a large, deep, smooth reflector – but the XR-E is still king in the throw department thanks to it handling more power than the XP-E and having a tighter viewing angle than the XP-G .

The bigger emitters like the SST50 and XM-L can be made to throw well – because the emitters are bigger and the viewing angle wider, a larger, deeper reflector is needed to catch all that light and collimate it into a useful, tight beam. Where they can partially make up for a lack of a concentrated beam is with the sheer amount of light that comes out the front. But the right sort of reflector is very important. Remember too that these emitters swallow a lot of power to make that amount of light – meaning battery life is short.

Torches with multiple emitters – you see some torches that have four emitters and reflectors in one large head unit, claiming big lumen numbers. If you look closely, you will notice that the reflectors are quite shallow and may even be textured. This does not make a long range spot beam. While good for lighting up an entire back yard, they won’t put a spot beam on a fox at 150m, and they also burn through the batteries.

Coloured emitters – you can get coloured LED’s such as red, green and blue. The most common versions made by Cree will unfortunately not handle as much power as the white version, so they don’t put out as much light. They can still be useful for shorter range hunting use such as on airguns or if teamed with an aspheric lens they can project a useful spot to about 100m. Certain colours can be useful for game that may be spooked by a white light, or may show up animal eyes better than white light.

Batteries – there are lots of different battery options for torches. Many cheaper lights will run on several batteries, most commonly three or four AAA’s. They can work OK, but those little batteries can only power a light for so long. While the voltage of four AAA’s is quite high (1.5v x 4 = 6v) the capacity in mAH is quite low. So they run down quickly.

Milliamps Hour (mAh) is important because it's the easiest way to distinguish the strength or capacity of a battery. The higher the mAh, the longer the battery will last. Batteries with different mAh ratings are interchangeable. If your battery is rechargeable then the mAh rating is how long the battery will last per charge. Think of a cars petrol tank. Voltage is how much petrol is being used, and mAh is the size of the petrol tank. The bigger the petrol tank (mAh) rating the longer the device will run.

Some lights have the option of running different sorts of batteries. Most commonly, it will be two of the small rechargeable RCR123 batteries, two non rechargeable CR123’s or a single 18650 battery. Non rechargeable CR123’s were common in cameras and are still widely available. Voltage for the RCR123 is around 3.6V, capacity is only 700 mAH. The big 18650 is I guess you’d say the diesel engine of torch batteries. These are often used in laptops, to give you an idea of their staying power. They are called 18650’s because they are 18mm in diameter and 65mm long. Voltage is 3.7V and capacity is generally 2400 mAH. So you get a good runtime and of course unlike throw away batteries you can recharge them over and over.

What torch for what gun? Well, how much light you project, and how far, is going to be governed by how far you need to see and need to shoot. On a .22LR or an airgun, even a tightly focused 50 - 75 lumens will let you shoot at 50m or more. A compact torch with a conventional lens and a tightly focused 200 lumens will let you shoot at over 100m. Add an aspheric lens or a large, smooth reflector to collimate the beam, and you can shoot at 200m. These are ranges where you can clearly identify your target through a scope – not just get eyeshine. Eyes like those of foxes or cats will show up several hundred metres away. Again, light intensity is important moreso than huge lumen figures – you aren’t really looking to light up half the paddock with a rifle mounted torch, just your target and a bit of the surroundings.

I won’t go into detail about which torch is best, and so on – there are many, many choices and what you need will be dictated by your intended usage and your budget. A torch that will work well on a .223 for longer shots won’t be ideal on a 12g shotgun on bunnies, for example. On top of all that, there are new lights coming out all the time – new LED emitters, new focusing system and so on.

I hope this little guide might be of use to someone.

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That's enlightening Fenring. Is there a spot for that in the Wiki? It would be a great reference for the future and save a lot of time.

Grant

P.S. I just checked, there is a spot, Optics and lighting. How about posting it there Fenring?

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Guest bigfellascott

Excellent write-up Dan. A lot of effort gone into that mate, I appreciate it and I'm sure the others who use the info will too. :goodjob::goodjob::goodjob:

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Glad you found it informative guys. There's a lot of scuttlebutt and disinformation out there about lights - as well as ads that claim outrageous things. Ebay is loaded with torches that claim huge lumens, so folks often assume they will be good for spotlighting but it's not necessarily so.

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Good post. I just bought a couple of cheap torches for work after losing my last one on a job the other day. Should have read the post before deciding on which new one to get, I was flying blind a bit with all the stats etc. Good for future reference.

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Thanks mate. There's a bit about batteries above. The higher the mAh, the greater the capacity of the battery. They also take longer to charge, no way around that really.

Some 18650 batteries are "protected" - they have a small printed circuit board on the bottom that prevents over discharge or over charging.

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