ZL SC600 quite impressive but I don't really get "lumens"...

witness · Apr 28, 2012

I just took the Zebralight SC600 (that was shipped to me by mistake instead of the SC600w) down to an unlit beach park and compared it to my H600 and MiniX123. I don't understand why but, it significantly out throws the H600 even though it only has 70 extra lumens. What I find really puzzling is the fact that there seems to be a larger difference between the 430 lumen H600 and 500 lumen SC600 than there is between the 500 and 750 lumen setting of the SC600. Also, while the difference between the 210 lumen MiniX123 and 500 lumen SC600 is quite significant, the tiny 70 lumen difference between the SC600 and H600 seems similar in magnitude (at least subjectively). I don't really get it.

THE_dAY · Apr 28, 2012

That is throw (lux) what you are comparing outdoors not brightness (lumens).
Just like a 2000 lumen light bulb won't throw as far as a 50 lumen flashlight yet the light bulb is brighter.

Basically, the larger the reflector the more throw it will give. The SC600 will throw further because it has a larger reflector compared to the H600.

One method to get an understanding of lumen output between lights is the ceiling bounce.
Go into a room, the smaller the better, but a bedroom should work fine. Point each light at the ceiling one at a time and look at how much they light up the room overall. This will give a better idea on how each light compares in brightness (lumens).

peterharvey73 · Apr 28, 2012

Light has three different factors:
1) intensity in units called Lux,
2) surface area illuminated in square meters,
3) the total volume of light in units called lumens.

The total volume of light [lumens] = the intensity [lux] x the lateral surface area illuminated [square meters].
Thus, the higher the intensity, the greater the volume of light in lumens.
The larger the surface area illuminated, also the greater the volume in lumens.
The volume in lumens takes into account both the intensity in lux, and the surface area illuminated in square meters.
It's like F = ma, force equals mass multiplied by acceleration.

The intensity of light in lux, will determine the longitudinal throw.
The higher the intensity of light, the further it will throw longitudinally.

Aka Gearbox
Your three flashlights may have similar total volume lumen outputs, however the reflector sizes are different.
The reflector concentrates the light into a central hot spot to increase the intensity in lux of that central hot spot so that it can throw further longitudinally, at the cost of reducing the lateral surface area of illumination, in other words the side ways spill.

Thus, the reflector is similar to the gearbox of a motor car.
First gear increases the torque, at the expense of reducing the rpm speed.
However, always remember that a gearbox does not change the total power output of a motor car; the total power output remains the same.
In the same way, a reflector does not change the total volume lumen count; the total volume lumen count remains the same.
The reflector merely increases the intensity in lux, at the expense of reducing the lateral surface area of illumination in square meters.

When the three flashlights have different size reflectors, the throw is different, but you will also find that the lateral surface area of illumination in square meters is changed too; meanwhile the total volume of light, which takes into account both factors, should remain the same.

The bigger the reflector, the smaller and more intense the hotspot.
The deeper the reflector relative to the width, also the more intense the hotspot, but more importantly, the lateral spill of illumination is dramatically reduced, and this light creates a "corona" which is a secondary ring/band of light surrounding the hotspot.
Thus, the more relatively deeper reflector delivers a narrower spill of light, but a larger and more intense corona ring of light surrounding the hotspot.

Thus, the hotspot is light that is captured by the reflector, and then focused into a central hotspot.
The corona surrounding the hotpsot is created by a relatively deep reflector that captures the lateral spill of light, and focuses it onto the corona ring of light.
The lateral spill is light that is transmitted directly from the emitter itself, without being reflected from the reflector at all.

Because the reflector does not reflect 100% of the light emitted, there is some efficiency loss.

Lens
The light then passes through the lens.
The lens can be flat.
It can also be TIR total internal reflection optics used by Surefire.
The lens can also be aspherical [like a camera lens], in which case there will be no reflector at all.

TIR hybrid reflector and lens combinations deliver a very intense and wide hotspot, but very little lateral spill.
Thus, it is great for hunting and long range rifle shooting through a scope.
Surefire TIR's are commonly used by the US Military.

Aspherical lenses with no reflectors at all, delivers the greatest intensity, with the greatest longitudinal throw, but there is almost no spill at all.

Thus, conventional flashlights use a reflector, and a flat lens only, for a combination of a decent hotspot for decent throw, plus a decent lateral surface area of illumination.

The Common Confusion
The greatest confusion tends to come from the term "brightness".
Because brightness can mean a great total volume of light in lumens.
Brightness can also mean greater intensity of light in lux.
Hence the confusion.
Thus, I have deliberately avoided using the term "brightness" above.
I have only referred to the total volume of light in lumens, and the intensity of light in lux...

Fireclaw18 · Apr 28, 2012

From a layman's perspective:
1. Go outside and shine the light on something off in the distance. The one that makes it brighter has higher lux.
2. Go into a dark room and hold one light in each hand. hold your arms straight out in front of you and point the lights at the ceiling. Turn one light on then off, repeat with the other light. As you do this look at an object on the floor below the lights. Do not look at the lights directly. The light that makes the object brighter has more lumens.

A light can have high lumens with low lux (a floodlight). An example would be a flashlight with a frosted lens that emits a wall of light that lights up everything around the flashlight but nothing in the distance.
A light can have high lux with low lumens (a spotlight). An example would be a flashlight with an aspheric lens that projects an image of the die with no spillbeam.

Sometimes telling gains in brightness is difficult. The eyes don't perceive brightness in a linear scale. A light needs to output around 20% more light before the difference in brightness becomes noticeable. And to perceive a light as being twice as bright to the eye, you need far more than twice as many lumens.

witness · Apr 28, 2012

Thanx so much eveyone. I really appreciate people taking the time to answer a newb question. Peterharvey, wow!! What a great and detailed responce. :sssh:

HighlanderNorth · Apr 28, 2012

peterharvey73 said:
Light has three different factors:
1) intensity in units called Lux,
2) surface area illuminated in square meters,
3) the total volume of light in units called lumens.

The total volume of light [lumens] = the intensity [lux] x the lateral surface area illuminated [square meters].
Thus, the higher the intensity, the greater the volume of light in lumens.
The larger the surface area illuminated, also the greater the volume in lumens.
The volume in lumens takes into account both the intensity in lux, and the surface area illuminated in square meters.
It's like F = ma, force equals mass multiplied by acceleration.

The intensity of light in lux, will determine the longitudinal throw.
The higher the intensity of light, the further it will throw longitudinally.

Aka Gearbox
Your three flashlights may have similar total volume lumen outputs, however the reflector sizes are different.
The reflector concentrates the light into a central hot spot to increase the intensity in lux of that central hot spot so that it can throw further longitudinally, at the cost of reducing the lateral surface area of illumination, in other words the side ways spill.

Thus, the reflector is similar to the gearbox of a motor car.
First gear increases the torque, at the expense of reducing the rpm speed.
However, always remember that a gearbox does not change the total power output of a motor car; the total power output remains the same.
In the same way, a reflector does not change the total volume lumen count; the total volume lumen count remains the same.
The reflector merely increases the intensity in lux, at the expense of reducing the lateral surface area of illumination in square meters.

When the three flashlights have different size reflectors, the throw is different, but you will also find that the lateral surface area of illumination in square meters is changed too; meanwhile the total volume of light, which takes into account both factors, should remain the same.

The bigger the reflector, the smaller and more intense the hotspot.
The deeper the reflector relative to the width, also the more intense the hotspot, but more importantly, the lateral spill of illumination is dramatically reduced, and this light creates a "corona" which is a secondary ring/band of light surrounding the hotspot.
Thus, the more relatively deeper reflector delivers a narrower spill of light, but a larger and more intense corona ring of light surrounding the hotspot.

Thus, the hotspot is light that is captured by the reflector, and then focused into a central hotspot.
The corona surrounding the hotpsot is created by a relatively deep reflector that captures the lateral spill of light, and focuses it onto the corona ring of light.
The lateral spill is light that is transmitted directly from the emitter itself, without being reflected from the reflector at all.

Because the reflector does not reflect 100% of the light emitted, there is some efficiency loss.

Lens
The light then passes through the lens.
The lens can be flat.
It can also be TIR total internal reflection optics used by Surefire.
The lens can also be aspherical [like a camera lens], in which case there will be no reflector at all.

TIR hybrid reflector and lens combinations deliver a very intense and wide hotspot, but very little lateral spill.
Thus, it is great for hunting and long range rifle shooting through a scope.
Surefire TIR's are commonly used by the US Military.

Aspherical lenses with no reflectors at all, delivers the greatest intensity, with the greatest longitudinal throw, but there is almost no spill at all.

Thus, conventional flashlights use a reflector, and a flat lens only, for a combination of a decent hotspot for decent throw, plus a decent lateral surface area of illumination.

The Common Confusion
The greatest confusion tends to come from the term "brightness".
Because brightness can mean a great total volume of light in lumens.
Brightness can also mean greater intensity of light in lux.
Hence the confusion.
Thus, I have deliberately avoided using the term "brightness" above.
I have only referred to the total volume of light in lumens, and the intensity of light in lux...

I think I understand...

So you're saying that my truck has 450 lux in 1st gear, but if I upshift to a higher gear, then I increase the lumens! Right?

Seriously though, that was the most easily understood analogy I've heard and it really is pretty simple. You could also compare it to your garden hose I guess.

HighlanderNorth · Apr 28, 2012

Fireclaw18 said:
From a layman's perspective:
1. Go outside and shine the light on something off in the distance. The one that makes it brighter has higher lux.
2. Go into a dark room and hold one light in each hand. hold your arms straight out in front of you and point the lights at the ceiling. Turn one light on then off, repeat with the other light. As you do this look at an object on the floor below the lights. Do not look at the lights directly. The light that makes the object brighter has more lumens.

A light can have high lumens with low lux (a floodlight). An example would be a flashlight with a frosted lens that emits a wall of light that lights up everything around the flashlight but nothing in the distance.
A light can have high lux with low lumens (a spotlight). An example would be a flashlight with an aspheric lens that projects an image of the die with no spillbeam.

Sometimes telling gains in brightness is difficult. The eyes don't perceive brightness in a linear scale. A light needs to output around 20% more light before the difference in brightness becomes noticeable. And to perceive a light as being twice as bright to the eye, you need far more than twice as many lumens.

I just received my Sc600 yesterday, and although it is much brighter(higher lumens) than my Jetbeam BC-10, my BC-10 seems to almost out throw the SC-600, even though the BC-10 has a smaller diameter refector than the SC600. The BC-10's hot spot is smaller and more concentrated than the SC600's hot spot.

But that brings me to something I read a few months ago, that an LED with a smaller emitter will have more throw compared with an LED with a larger emitter in the same size reflector.

Well, although my BC-10 has a smaller reflector by about 50%, it's XPG-R5 LED has a much smaller emitter than the XM-L in my SC600, so the BC-10 has seemingly more throw on high.

witness · Apr 29, 2012

HighlanderNorth said:
I think I understand...

So you're saying that my truck has 450 lux in 1st gear, but if I upshift to a higher gear, then I increase the lumens! Right?

Seriously though, that was the most easily understood analogy I've heard and it really is pretty simple. You could also compare it to your garden hose I guess.

No, I think Peter is saying that the lumens remain constant and "upshifting" (changing the reflector to get a more concentrated light) increases the intensity(lux) but over a smaller area (which equates to more throw). I think this is what he said. :sssh:

jhc37013 · Apr 29, 2012

HighlanderNorth said:
I just received my Sc600 yesterday, and although it is much brighter(higher lumens) than my Jetbeam BC-10, my BC-10 seems to almost out throw the SC-600, even though the BC-10 has a smaller diameter refector than the SC600. The BC-10's hot spot is smaller and more concentrated than the SC600's hot spot.

But that brings me to something I read a few months ago, that an LED with a smaller emitter will have more throw compared with an LED with a larger emitter in the same size reflector.

Well, although my BC-10 has a smaller reflector by about 50%, it's XPG-R5 LED has a much smaller emitter than the XM-L in my SC600, so the BC-10 has seemingly more throw on high.

That's right the smaller the die size of the emitter the better the throw compared to a larger die sized emitter with the same reflector, there is so many things that can change a beam profile and the finding the emitter/reflector that makes you happy is like a great quest at times.

peterharvey73 · Apr 29, 2012

Physics
Hilander, wen u upshift gears, there is less torque, but more rpm speed; the total power output always remains the same - less some frictional and heat loss.
Similarly, wif a bigger reflector, there is greater intensity in lux, but the surface area of illumination in square meters is reduced; meanwhile d total volume of lumens always remains unchanged - less some efficiency losses thru the reflector & lens.

BC10 vs SC600 Throw
Yr BC10 wif XP-G R5 has a 23mm bezel diameter, but throws 167 meters as measured by Selfbuilt.
Yr SC600 XM-L has a 30mm bezel diameter, but only throws 145 meters as measured by Selfbuilt.
Personally, I have an RRT-0 XP-G S2 which is related to the BC10, and I also have an SC600 as EDC.
I am waiting on a future enhanced RRT-01 powered by an 18350 with OP reflector as a future EDC.

Emitters XP-G vs XM-L
When both types of emitters are driven to their maximum recommended amperage respectively, namely 3 amps for the XM-L and 1.5 amps for the XP-G, the larger sized 2mm x 2mm XM-L emitter actually has greater surface brightness or intensity in lux than the smaller roughly 1.25mm x 1.25mm XP-G emitter.
In this case, we know that the SC600 is driven to the maximum recommended 3 amps for 750 lumens OTF.
However, I don't know if the BC10 has been driven to its maximum recommended amperage of 1.5 amps or not?
It will probably be 1.5 amps, or less.
In either case, the SC600 should definitely have higher surface brightness, hence higher intensity in lux originating from the emitter for greater throw.
Also theoretically, the wider diameter reflector of the SC600 should make a smaller and more intense hotspot, for greater longitudinal throw too.
Yet ironically, it is the BC10 with the less surface brightness XP-G emitter and the smaller diameter reflector that actually throws further!
Why? Enter the role of the reflector relative depth, and orange peel stippling of the surface of the reflector.

Reflector Depth to Width Ratio [Relative Depth]
The greater throw of the BC10 is due to the BC10's relatively deeper reflector, ie deeper refector depth to width ratio, hence narrower spill, the more prominent secondary band of corona, and the brighter hotspot, consequently the greater throw.
The SC600 has a very shallow reflector for a bigger hotspot and wider lateral spill, but poor longitudinal throw.

Orange Peel LOP, MOP & HOP Reflectors
Another factor that diminishes the SC600's throw is the medium orange peel MOP reflector, where the more heavily stippled reflector diffuses the light more, thus reducing the intensity of d hotspot.
Remember that d BC10 has either only a smooth SMO, or only light orange peel LOP reflector, for greater throw, but more rings and artefacts in its beam.
If a Heavy Orange Peel HOP reflector were fitted to the SC600, its throw would be diminished even further...

ZL SC600 quite impressive but I don't really get "lumens"...

witness

Newly Enlightened

THE_dAY

Flashlight Enthusiast

peterharvey73

Flashlight Enthusiast

Fireclaw18

Flashlight Enthusiast

witness

Newly Enlightened

HighlanderNorth

Flashlight Enthusiast

HighlanderNorth

Flashlight Enthusiast

witness

Newly Enlightened

jhc37013

Flashlight Enthusiast

peterharvey73

Flashlight Enthusiast

Similar threads

Latest posts