Before you buy a light online, how do you figure out its throw/flood characteristics?

HighlanderNorth

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I just bought the Jetbeam BC-10 last week, and the iTp A6 Polestar this week. I've compared both lights, and it's obvious that the BC-10's reflector is deeper compared to it's diameter, causing it's secondary luminosity area(dont know the true term for what I'm talking about here) to be smaller and throw further, whereas the Polestar has a shallower reflector, causing it's secondary luminosity area to be wider and shorter range.

But the brighter, smaller primary area of luminosity at the center of the light patterns(dont know the term for that either) of both lights is pretty close, and they have throw from that standpoint, but the Polestar is better at lighting up shorter range areas with its secondary area of luminosity, and the BC-10 is better at lighting up medium to longer range areas with its secondary area of luminosity.

But how do you tell beforehand what the flood/throw characteristics will be, before you buy the light?
 

KeyGrip

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There are certain assumptions you can make based on the light source and the optics of the light, but for the most part yowzer has it spot on. If it's a halfway decent light, it'll have a review or two to look at before purchasing.
 

orbital

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+

Just buy one of the many focusable lights
:D
Seriously,,,
probably the first good question in months on CPF

The emitter is important, XP-E & XR-E will give the best throw,
but more importantly is the difference in size between the emitter and reflector.
~ The greater the difference in size, the likelihood of more focused beam.
Reflector depth is a big factor, the classic throwers have an uber deep reflector.

XP-G & XM-L are better at floody setups, but this is not exclusive, they can throw too, but its trickier.


...I'll likely edit this post as I think 'o stuff
 
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davecroft

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This is how I do it:
1. Look at reviews on CPF
2. Check out the videos on YouTube (especially the Going Gear ones)
3. Look at the very useful Russian website - fonarik.com I think its called - has some great beamshot comparisons.
 
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weez82

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This is what I do before I buy a light.
Step one: selfbuilt reviews (in the review section)
Step Two: youtube (goingprepared)
 

Chidwack

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I know what you are talking about. I have been in somewhat the same situation. Yes you can read up and watch video's on the different lights as long as they are the lights you are thinking of getting but sometimes there are lights that haven't had reviews that I can find. Also it's hard to really get a feel for the throw of a light without actually experiencing it. I'm a throw freak too and from what I can see, there are throw lights and then there are THROW lights. You kinda have to decide which size or which battery or how many batteries you want. Then you can read up and ask here on this board and get a pretty good idea. Also, the price you are willing to spend comes into play. I couldn't afford some of the higher dollar throw lights. I ended up with a Jetbeam BC40. It's a 2x 18650 light but it is smaller than it looked on the video's. I know there are longer throw lights out there but I'm not sure you can get more throw for the buck than the Jetbeam BC40.
 

dosei-45

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I've found the reviews by goingprepared on youtube to be very helpful, since he stands in the same place in his yard at night and shines the lights at the same things in every review...makes comparing the beams/throw/spill rather easy.
 

Juan334

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just get the name of the light and emitter and put it in google and type review after it and some should pop up and if you cant find any click videos up top

i do that all the time
 

peterharvey73

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Try going to www.goinggear.com and have a look at the flashlights there.
Marshall has some very good videos on how the flashlights function and perform.

Go to www.youtube.com and see if you can search for a video demonstration of the flashlight there.

When you look at the videos, look for 4 characteristics:
1. hot spot brightness,
2. hot spot size,
3. spill brightness,
4. spill size.

It is the hot spot brightness that will single-handedly decide how far the beam will throw.
The hot spot size, and the spill brightness/width gives practicality.

Also remember that the later spill/flood beam, comes from light that is directly emitted from the emitter itself.
Whereas, the hot spot beam, comes from light that is indirectly reflected via the reflector!

The hot spot brightness is determined by the surface brightness of the emitter - how many lumens it produces relative to the LED emitter die size.
Remember that the:
Cree XR-E R2 is 1mm x 1mm,
XP-G R5 is 1.3mm x 1.3mm,
XM-L is 2mm x 2mm
MC-E is made of four smaller emitters arranged in a square; not sure what it's final dimensions are, but probably around 2mm x 2mm.
Luminuous SST-50 is 2.25mm x 2.25mm,
SST-90 is 3mm x 3mm.

The surface brightness in lumens per square millimeter of the emitter is one of two major factors that determines the brightness of the hot spot, and ultimately how far it throws.
The other factor that influences hot spot brightness and hence throw is the reflector.
The reflector collects light from the emitter, and focuses it into a central hot spot.
The larger the diameter of the reflector, the more light it will collect from the emitter.

NB.
When I first entered this forum, I used to incorrectly think that it was the difference in size of the emitter to reflector that determines the throw; this is incorrect.
It is actually the out-right size and hence diameter of the reflector that determines how much light is collected, and focused into the central hot spot.

The depth of the reflector?
It's not the depth of the reflector alone, but the depth of the reflector relative to it's width diameter.
A relatively deep reflector will have less side spill.
However, a relatively deep reflector will create a more prominent secondary ring of light around the hot spot called a "corona"!
The deeper the reflector, the greater the corona.
The corona helps to increase the overall lateral spill of light, but it does not influence the hot spot, nor the throw.

The size of the emitter determines the hot spot size.
The brightness of the emitter determines the spill brightness.
While the relative depth of the reflector determines the spill width.

Practically:
The Jb BC10 is a small pocket sized flashlight, powered by a single CR123/16340 size battery 3.0 volts primary disposable, or 3.7 volts rechargeable.
It has a Cree XP-G R5 emitter, and a relatively small diameter reflector less than an inch, but a relatively deep reflector at that.
Thus, the BC10 will deliver a fairly bright hot spot with good throw - Selfbuilt measures it to be 167 meters to ANSI standards.
Because the XP-G emitter is small to medium sized, the hot spot will be small to medium sized.
Because the BC10's reflector is relatively deep, it will have a narrower side spill, but it will have a prominent secondary "corona" encircling the hot spot.

The ITP A6 Polestar is a medium size flashlight powered by 6x AA batteries, arranged in two rows of three in parallel, powering a Cree MC-E emitter that is made up of four smaller emitters, all housed in a medium sized bezel diameter of 48 mm!
Because the MC-E emitter is made up of four smaller emitters, it has a very large surface area, hence the surface brightness of the MC-E is weak, hence the hot spot is less intense, and the throw is poor.
Although the ITP A6 has a decent medium sized 48mm diameter reflector, it just isn't enough to compensate for the lesser surface brightness of the MC-E emitter.
However, because the MC-E is so large in square millimeter size, the hot spot is quite large, and larger than the BC10 XP-G R5's.
Because the ITP A6 has a relatively shallow reflector, it's side spill is broad, and it will have a less prominent corona encircling the hot spot.
Because the MC-E is actually made up of four smaller emitters, it's total lumen output is a whopping 700 lumens, thus it has a bright side spill of light...
 
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HighlanderNorth

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Try going to www.goinggear.com and have a look at the flashlights there.
Marshall has some very good videos on how the flashlights function and perform.

Go to www.youtube.com and see if you can search for a video demonstration of the flashlight there.

When you look at the videos, look for 4 characteristics:
1. hot spot brightness,
2. hot spot size,
3. spill brightness,
4. spill size.

It is the hot spot brightness that will single-handedly decide how far the beam will throw.
The hot spot size, and the spill brightness/width gives practicality.

Also remember that the later spill/flood beam, comes from light that is directly emitted from the emitter itself.
Whereas, the hot spot beam, comes from light that is indirectly reflected via the reflector!

The hot spot brightness is determined by the surface brightness of the emitter - how many lumens it produces relative to the LED emitter die size.
Remember that the:
Cree XR-E R2 is 1mm x 1mm,
XP-G R5 is 1.3mm x 1.3mm,
XM-L is 2mm x 2mm
MC-E is made of four smaller emitters arranged in a square; not sure what it's final dimensions are, but probably around 2mm x 2mm.
Luminuous SST-50 is 2.25mm x 2.25mm,
SST-90 is 3mm x 3mm.

The surface brightness in lumens per square millimeter of the emitter is one of two major factors that determines the brightness of the hot spot, and ultimately how far it throws.
The other factor that influences hot spot brightness and hence throw is the reflector.
The reflector collects light from the emitter, and focuses it into a central hot spot.
The larger the diameter of the reflector, the more light it will collect from the emitter.

NB.
When I first entered this forum, I used to incorrectly think that it was the difference in size of the emitter to reflector that determines the throw; this is incorrect.
It is actually the out-right size and hence diameter of the reflector that determines how much light is collected, and focused into the central hot spot.

The depth of the reflector?
It's not the depth of the reflector alone, but the depth of the reflector relative to it's width diameter.
A relatively deep reflector will have less side spill.
However, a relatively deep reflector will create a more prominent secondary ring of light around the hot spot called a "corona"!
The deeper the reflector, the greater the corona.
The corona helps to increase the overall lateral spill of light, but it does not influence the hot spot, nor the throw.

The size of the emitter determines the hot spot size.
The brightness of the emitter determines the spill brightness.
While the relative depth of the reflector determines the spill width.

Practically:
The Jb BC10 is a small pocket sized flashlight, powered by a single CR123/16340 size battery 3.0 volts primary disposable, or 3.7 volts rechargeable.
It has a Cree XP-G R5 emitter, and a relatively small diameter reflector less than an inch, but a relatively deep reflector at that.
Thus, the BC10 will deliver a fairly bright hot spot with good throw - Selfbuilt measures it to be 167 meters to ANSI standards.
Because the XP-G emitter is small to medium sized, the hot spot will be small to medium sized.
Because the BC10's reflector is relatively deep, it will have a narrower side spill, but it will have a prominent secondary "corona" encircling the hot spot.

The ITP A6 Polestar is a medium size flashlight powered by 6x AA batteries, arranged in two rows of three in parallel, powering a Cree MC-E emitter that is made up of four smaller emitters, all housed in a medium sized bezel diameter of 48 mm!
Because the MC-E emitter is made up of four smaller emitters, it has a very large surface area, hence the surface brightness of the MC-E is weak, hence the hot spot is less intense, and the throw is poor.
Although the ITP A6 has a decent medium sized 48mm diameter reflector, it just isn't enough to compensate for the lesser surface brightness of the MC-E emitter.
However, because the MC-E is so large in square millimeter size, the hot spot is quite large, and larger than the BC10 XP-G R5's.
Because the ITP A6 has a relatively shallow reflector, it's side spill is broad, and it will have a less prominent corona encircling the hot spot.
Because the MC-E is actually made up of four smaller emitters, it's total lumen output is a whopping 700 lumens, thus it has a bright side spill of light...

Thanks.........

That's a lot to take in, but it makes sense.........

I actually like both the BC-10 and the A6 Polestar(with the exception of its weak and cheap battery container), but I wish the Polestar had more throw and better mid range illumination, like the less powerful BC-10 has.
 

peterharvey73

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Generally, I would have avoided the MC-E emitter in the Polestar, because the MC-E is old, and has been largely replaced by the XM-L model which will give you the mid-range and the throw you want in a medium sized flashlight...
 

ShineOnYouCrazyDiamond

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I would say that some of it is based on experience.

- Know what emitter is being used - this is the first gauge to determine if the light will be a thrower or a flooder.
- Next look at size. I tinier light will generally be more floody that a big one.
- Look at the diameter of the head.
- A wider head will generally have more throw.
- A deeper head will generally have a smaller flood area.

Ultimately, sometimes, just buying the light and trying it out is really the best way. Compare it with what you have. Do you like the UI, the throw, the spot size, the amount of light in the flood, the size of the flood, etc. If yes, the it's a keeper. If no, then up on the CPFMP BST thread it goes. Sometimes it's worth the $5-10 to just try out a light.
 

SimulatedZero

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Sorry for reviving an old thread. A little trick that I have found (and I may be wrong in this but it seems to work fine) is to do a ratio of Candela per Lumen. In example my Fenix E21 and Fenix TK15 throw fairly well (especially the E21, relative to how bright and cheap it is (XP-E emitter)). Both of those lights roughly have a 33cd/lumen ratio (just keeping it simple and rounding to two sig figs I know it's not 100% accurate). The new maglite D-Cell LED is a great thrower and not a bad light to be honest. It puts out 131 lumens and I can light up 500ft with it pretty easily, only problem is that when it is fully focused it has to small of a hot spot to see things well up close. The maglite has a 234cd/lumen ration, roughly. Most tactical lights tend to be somewhere between 10 and 100 cd/lumen. I don't know how realistic this is but it helps me narrow down lights to the style hotspot I want quickly and then pick apart the tiniest details from there. 33cd/lumen or 34cd/lumen will have fairly nice throw but not the best. It will, however, put a nice fat hotspot on whatever you are looking at and light it up really well, especially in the brighter lights (300+ lumens). But that is just based off of my personal experience, it would be interesting to see if anybody has noticed the same thing or has evidence to the contrary.
 

gcbryan

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Sorry for reviving an old thread. A little trick that I have found (and I may be wrong in this but it seems to work fine) is to do a ratio of Candela per Lumen. In example my Fenix E21 and Fenix TK15 throw fairly well (especially the E21, relative to how bright and cheap it is (XP-E emitter)). Both of those lights roughly have a 33cd/lumen ratio (just keeping it simple and rounding to two sig figs I know it's not 100% accurate). The new maglite D-Cell LED is a great thrower and not a bad light to be honest. It puts out 131 lumens and I can light up 500ft with it pretty easily, only problem is that when it is fully focused it has to small of a hot spot to see things well up close. The maglite has a 234cd/lumen ration, roughly. Most tactical lights tend to be somewhere between 10 and 100 cd/lumen. I don't know how realistic this is but it helps me narrow down lights to the style hotspot I want quickly and then pick apart the tiniest details from there. 33cd/lumen or 34cd/lumen will have fairly nice throw but not the best. It will, however, put a nice fat hotspot on whatever you are looking at and light it up really well, especially in the brighter lights (300+ lumens). But that is just based off of my personal experience, it would be interesting to see if anybody has noticed the same thing or has evidence to the contrary.

It's not really telling you anything as different emitters come out and in any event you don't need a ratio if you already have access to cd and lumen numbers. High cd will throw. That's the definition of throw. High lumen will give you higher output that's the definition of output.

A lower cd/lumen ratio just means a bigger emitter. It may throw just as far and have more flood and a bigger hotspot.

If you know cd you know throw and can compare it with other lights in that regard. If you know lumens then you really just have to look at the reflector. If it's deep and wide there is less spill. If it's a smaller reflector then it's mainly flood.
 

peterharvey73

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GC is right.
Candelas are a direct measure of both brightness/intensity and longitudinal throw.

Candelas and lux are both measures of brightness or intensity of light.
The difference is that one Candela is one lumen per steradian angle, whereas one lux is one lumen per square meter.
Candelas can be converted into lux, and vice versa, if the distance and steradian angle is known.
Here is a Candela to lux calculator: http://www.ledrise.com/shop_content.php?coID=18



Now, about those lumens.
Remember how mechanical power in a motor car engine = mass x acceleration x speed.
In other words, power = force x speed.
Or power = torque divided by time.
Likewise, electrical power = voltage x current (in Amps).
Similarly, the total power of light (in lumens) = the brightness/intensity (in lux) multiplied by the surface area of illumination (in square meters).
The brightness/intensity in lux is the total lumens per square meter.
The brightness/instensity in lux determines the longitudinal throw.
The brightness/intensity in Candelas also determines the longitudinal throw.
The total lumens gives you an idea of the product of the brightness in lux, and the size of the surface area illuminated in square meters.
Lumens gives you an idea of both the lux and the surface area illuminated, combined in one total.



Now, your formula of Candelas divided by lumens factor?
Is basically lux divided by lumens.
One lux is one lumen per square meter.
Thus, lux divided by lumens = (lumens per surface area in square meters) divided by lumens.
This equals (lumens per surface area) multiplied by (1/lumens).
Note the lumens cancel out, leaving you with (1/the surface area); that is, the inverse of the surface area of illumination.
Thus, if I'm not wrong, your Candelas per lumen, is actually roughly equal to the inverse of the surface area illuminated.

If you invert your mathematics to lumens per Candela, or in other words, lumens per lux, this will give you the surface area of illumination alone.
Lumens = lux x surface area.
Surface Area = lumens divided by lux!
In other words, surface area = lumens/lux.
Which is similar to lumens per Candela, remembering that if the distance and steradian angle is known, then Candelas can be converted to lux, and vice versa.
One Candela is just one lumen per steradian, while one lux is one lumen per square meter.

Thus, rather than your original Candelas per lumen, try lumens per Candela, or even lumens per lux - this will give you a rough idea of the lateral surface area of illumination in square meters, or at least a surface area of illumination co-efficient for comparison purposes.
You know the total output in lumens, giving both the brightness in lux and the surface area of illumination, combined in one total.
You know that Candelas and lux are a measure of the brightness and hence longitudinal throw.
The higher the Candelas per lumen ratio, or lux per lumen ratio, the greater the surface area of illumination factor.

Your E21 XP-E with 25mm bezel diameter has 154 lumens output and 4510 Candelas for 134 meters of throw.
Meanwhile your TK15 XP-G with 34mm bezel has 337 lumens with 11592 Candelas for 215 meters of throw.
The TK15 has more Candelas, and throws further.
The TK15's total lumen output has roughly more than doubled too, because the brightness/intensity in Candelas has more than doubled.
Note that the TK15's reflector is larger, so the hotspot will be smaller and more intense for greater throw.
If the TK15's reflector has a deeper relative depth, then the spill will be narrower, the hotspot possibly even brighter still, or at least the corona will be more prominent.
If we calculate the lumens per Cd ratio, the E21 comes out at 0.0034, while TK15 is 0.0029; meaning that the E21 has more surface area of illumination, or spill; consistent with a smaller reflector.
So does the E21 have a wider spill than the TK15?
However it gets confusing, because the TK15 may have a larger hotspot than the E21?
Meanwhile we know that your Maglite has a high Candela, long throw, but very dim spill, but the lumen/Candela factor of 0.0043 says very little.
The reason the lumen/Candela, or your Candela/lumen factor says little is because the light beam is not uniform on the white wall.
The beam is inconsistent, with a concentrated hot spot of variable size, a less concentrated corona of variable size surrounding that hot spot, and a variable size and intensity spill.


Thus, when purchasing or comparing flashlights, the best way to compare their lateral performance or "spill", is not by numbers, but by white wall shots that are controlled.
For example, Selfbuilt keeps the flashlights 0.75 meters away from the white wall, while the camera is 1.25 meters away.
The aperture and shutter speed are known.
Then the beam on the white wall are compared.
Look for six factors: the intensity and size of the hotspot, the intensity and size of the corona surrounding the hotspot, and the intensity and size of the spill.
Unfortunately, there is presently no objective and quantitative way to measure the lateral spill of light on the spec sheet - only a subjective and qualitative controlled white wall shot found in flashlight tests and reviews...
 
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SimulatedZero

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All very excellent points from both of you and I appreciate the in depth analysis of the various equations peter, +1. For academics sake I measured (in centimeters) the diameter of the corona and hotspot on both the Fenix E21 and the Fenix TK15 at 75cm from a plain white wall. All figures are rounded to two significant figures to keep precision uniform and have a rough variance of +/- .5cm due to the measuring technique (tape measure). The E21 has a Corona diameter of 98cm and a Hotspot diameter of 7cm. The Fenix TK15 has a Corona diameter of 90cm and a Hotspot diameter of 7cm. The hotspot on the E21 was harder to measure because it had a smoother transition to the secondary? corona around it. The TK15s hotspot is a clear cut circle of light with a slight doughnut hole. The overall corona is much more intense on the TK15 and creates a wall of light effect outside. It almost gives the light a floody feeling on turbo despite the tight hotspot and solid throw. I get the impression from the description gc gave that lights of equal candela will throw the same distance. In example if I have a 100 lumen light with 4000 candela and a 200 lumen light with 4000 candela they will both throw the same distance but the 200 lumen light will light up more surface area at that distance. Does this hold true? I appreciate the feed back on this guys, I know I find it helpful and hopefully others will too.

(P.S. flashlight manufacturers should all include an ANSI data chart and whitewall beam shots at a set distance (.75m, 1m) Kinda like Fenix does:twothumbs)
 

peterharvey73

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... I get the impression from the description gc gave that lights of equal candela will throw the same distance. In example if I have a 100 lumen light with 4000 candela and a 200 lumen light with 4000 candela they will both throw the same distance but the 200 lumen light will light up more surface area at that distance. Does this hold true? I appreciate the feed back on this guys, I know I find it helpful and hopefully others will too...

Yes, your understanding is absolutely correct.
They will both have the same hot spot intensity and throw the same longitudinal distance, but the light with 200 lumens will have a larger lateral surface area of illumination.
The larger lateral surface area of illumination can be manifested as: a larger hot spot, a brighter and/or larger corona secondary band of light, or a brighter and/or larger spill beam.
That 4000 Candelas is only a measurement of the brightness of a small area in the centre of the hot spot.
Because the beam of light on the white wall in not uniform, the other parts of the beam of light, like the width of the hot spot, the corona, and the spill, must also be measured and accounted for.
To do this, you'd have to divide your 1 meter by 1 meter square white wall, up into 100 squares, each 10 cm by 10 cm, and measure the lux from each 10 cm square.
The lux of each 10 cm square must then be multiplied by the surface area of each square at 0.1 x 0.1, and the product added to the product of the other 99 squares.
Then you have your total count in lumens.
This is provided the beam fits within that 1 meter square.
Notice that nobody measures total lumen output this way, because it is too difficult.
Usually, we measure either emitter lumens, or OTF lumens to take into account inefficiencies and losses in the reflector and lens...
 
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gcbryan

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Peter has answered your question correctly although your conclusions are slightly off. The light with more lumens won't necessarily have a larger area illuminated AT THAT DISTANCE as you state.

The surface area of the emitter and the focal length of the reflector/optic will determine that so that may or may not happen. As Peter points out it may just result in more spill or a larger corona.

If the hotspot isn't larger then the greater illuminated area won't be at the max distance. You will just have more spill or a larger corona at a closer distance. Which is likely to be the case in your example of 100 vs 200 lumens as they quite likely will be using the same emitter (XR-E for example). If you are talking about 200 lumens vs 800 lumens then you are probably talking about different emitters as well (XR-E vs XM-L for example) and therefore larger surface area in one (XM-L) and a larger hotspot.
 
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