Fenix TK21 (U2) 468lm look not as bright as P7 LED lenser

anylau · May 25, 2011

I needed help on this... today i got my TK21U2 edition flashlight... on turning on (with the new battery 2900ma 18650 before charge) the focus or hot spot dint look like more bright then my old P7 lenser focus hot spot... is like 468lm vs 200lm... and 200 looks brighter... hmmm could anyone shine some light on this issue for me?

I did not yet charge the new 18650 batt... does this affect? will it be brighter after i charge it? i assume it's regulated on the tk21.... so the brightness wont be affected...

do note all the beam shot is take just moment after i on my light... or do i need to let the xm-l u2 LED to warm up or something??

tomorrow my M7 will arrive... will do another test with that later on... (actually it just arrive while i was away from lunch...)

250941_10150204082444910_849719909_6830819_4329459_n.jpg

DimeRazorback · May 25, 2011

The LED Lenser has all of the light focused in one spot. The TK21 does not, as you can see.

Try doing a ceiling bounce test.

One at a time, shine the lights at the ceiling in a dark room. Observe how much you can see in the room from the light that is "bouncing" off the ceiling.

As it is clearly shown in your photo, the LED Lenser is extremely bright in just one spot, whereas your TK21 has a hotspot and spill...

You cannot truly compare the two for their "throw" as one has the ability to focus all of the light into a small area.

Based on your picture, I would say that the TK21 is close however, in terms of lux or "throw".

anylau · May 25, 2011

So this is normal right? because for me.. i tot i would like notice a BIG differences on 468 vs 200 lumen... hmmm maybe i need to go out door and do a couple of shots and see...

anyway.. really thank u for the reply~~~ this was my 1st post!!!

DimeRazorback · May 25, 2011

Like I'm saying, at the moment you are comparing the "throw" or Lux of the lights.

To compare the Lumens you need to conduct a ceiling bounce and see how well lit a dark room is with each light. This will show a comparison of "Lumens" more so.

For example, if you have your LED Lenser fully "unfocused" so that it is entirely flood, it will appear a lot less than the 468lm of the TK21...

Have a read through the Welcome Mat. :thumbsup:

Stephen Wallace · May 25, 2011

As Dime has stated, when talking about the lumen output of the light, an 'integrating sphere' is used, which captures and measures all the light being output - it isn't just about measuring the brightest point in the beam. So if you look at the beam profile of your TK21, you have a bright hotspot, and then a wide swath of paler spill light around that hotspot. ALL that light is measured to come up with the overall output. If the light were all concentrated in to the centre of the beam pattern, you would no doubt have a brighter hotspot. Obviously, if we reverse that, the more light is in the spill patterm the less light there will be in the hotspot, and the less bright the hotspot will be. Long story short, the TK21 IS putting more light out than the P7, but it is spreading that light over a wider area, rather than concentrating it in to one spot.

Another thing to consider is that your eyes do not perceive the brightness of light in a linear pattern. I'm not sure if this is true for at all brightness levels, but it is commonly stated that you need four times the lumens to see the light as being twice as bright, so even if the TK21's light beam were focussed as tightly as the P7's, the hotspot still wouldn't be twice as bright.

anylau · May 25, 2011

oh... seem to understand it more clearly now...

u are correct.. on flood mood... the lenser really is far far far more less brighter d...

learn something new on lumens comparison today!!

thanks!! ^^

anylau · May 25, 2011

Stephen Wallace said:
As Dime has stated, when talking about the lumen output of the light, an 'integrating sphere' is used, which captures and measures all the light being output - it isn't just about measuring the brightest point in the beam. So if you look at the beam profile of your TK21, you have a bright hotspot, and then a wide swath of paler spill light around that hotspot. ALL that light is measured to come up with the overall output. If the light were all concentrated in to the centre of the beam pattern, you would no doubt have a brighter hotspot. Obviously, if we reverse that, the more light is in the spill patterm the less light there will be in the hotspot, and the less bright the hotspot will be. Long story short, the TK21 IS putting more light out than the P7, but it is spreading that light over a wider area, rather than concentrating it in to one spot.

Another thing to consider is that your eyes do not perceive the brightness of light in a linear pattern. I'm not sure if this is true for at all brightness levels, but it is commonly stated that you need four times the lumens to see the light as being twice as bright, so even if the TK21's light beam were focussed as tightly as the P7's, the hotspot still wouldn't be twice as bright.

wow!! this really do make it more clear for me now~~ really do appreciate the info given!!

so tk21 is a semi throw/flood light... correct?

DimeRazorback · May 25, 2011

Well yes sorta, it has a bright hot spot for distance illumination and spill for peripheral vision.

Stephen Wallace · May 25, 2011

^^^
Yep. As the reflector is fixed rather than focusable, it could be optimised for throw or flood, or a compromise between the two - as in this case. So as Dime said, you have a defined hot spot to give some throw, but still have plenty of spill light to light a wide area. However, with that compromise, the spill light won't be as bright as a dedicated flood light, and the hot spot won't throw as far as a dedicated throw reflector or a focusable light adjusted for a tight beam. As the saying goes - 'jack of all trades but master of none'. On the whole though, if you don't need a dedicated flood or throw light, it is a good compromise. It's a good general purpose light.

anylau · May 25, 2011

Ya i think tk 21 more like a general light i guess... i like good throw light... but.. it's my 1st fenix...

on the other hand... i did do the lumens checking on the ceiling... you really can define the brightness level doing tat!! thanks ya!!!

anylau · May 25, 2011

Fenix TK21 (U2) memory issue... need advice...

just a quick question on my tk21(u2)...

if u on it on turbo mode... then it dim itself down to high mode automatically in a while.. like few second after on... then after no matter what mode u set.. it will not remember.. and will just go back to turbo mode mood when u on it later...

I haven't charge my new battery 186500 yet...

could this be the battery is low issue?

if u switch mode before the turbo mode auto dim down to high... then it will remember ur last setting...

is this normal??

thanks in advance...

DM51 · May 26, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

I've merged your 2 threads - you didn't need to start a second one on the same topic. I've moved the combined thread to LED Flashlights.

Jannis · May 26, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

anylau said:
just a quick question on my tk21(u2)...
Yes it does the same on mine, but only when the battery is low, try charge it, and it will stay on turbo.
if u on it on turbo mode... then it dim itself down to high mode automatically in a while.. like few second after on... then after no matter what mode u set.. it will not remember.. and will just go back to turbo mode mood when u on it later...

I haven't charge my new battery 186500 yet...

could this be the battery is low issue?

if u switch mode before the turbo mode auto dim down to high... then it will remember ur last setting...

is this normal??

thanks in advance...

ergotelis · May 26, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

anylau, after seeing the picture you posted, i would say that you are kidding us!

But this is ok by the time you are inexperienced with the techical details/data etc.

The picture shows clearly the difference!
Tk21 is much brighter overall!
The spot illumination of P7 is really useless in most cases, it can work only for specific situations, such as if you want to see if there is something on its place. Other than that, it creates the "tunnel" effect, where you can't see anything else except the hotspot.THough in case of P7, the focusing ability is good to provide general lighting.
On the other hand with fenix, you can do both, you have a vision of the whole area in front of you!

yliu · May 26, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

That's normal. My LedLenser M7 has the most intense focused light from my flashlights (maybe it will change after I get my TK35).

The center hotspot is brighter than my TK12 R5 and my TK45 (not a thrower

. Doing a ceiling bounce test would give you a clearer idea of the brightness of you torches.

As with the M7, there is no big difference between the P7 and M7 brightness (with NiMH batteries). What I found that the Turbo mode on the M7 doesn't work with alkaline batts. Also you get more output with Lithium or NiMH than with alkalines.

anylau · May 26, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

yup, thanks for the replies again... indeed i do the ceiling bouce test.. and tk21 is BRIGHT... really BRIGHT!!! hahahaha

yliu... i tested (tesco alkalines) batts on the M7... turbo mode do work! weee.... i also purchase 2x2 lithium energizer... but nothice the one expirer on 2034 another 2032... donno could i mix or not... hmm

BUT Could someone tell me on the TK21U2... memory issue? do the battery life will affected it from remembering my last light mode? i notice after it auto step down turbo to high... it wont able to remember my last setting... i need to switch mode before the auto step down then only i could able to make it remember my setting.... and now it could not go in to strobe mode also... do fenix light have this function where the batt are low all these happen? i have yet to charge my 18650 since bought...

wrf · May 27, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

anylau said:
[...]BUT Could someone tell me on the TK21U2... memory issue?[...]

Same behavior on one of my two lights. See also this thread.

anylau said:
[...]i have yet to charge my 18650 since bought... [...]

Are you playing with fire on purpose? Check out the Batteries forum for some GREAT advice as to what (and what NOT) to do with those cells.

anylau · May 29, 2011

Re: Fenix TK21 (U2) memory issue... need advice...

hehe... yup... i finally charge it .. when it gone around 3.64v... hahaha... if i dint have this forum... i donno what will happen to my lights...

quad088 · May 29, 2011

I own one LL MT7 and one TK21. In comparison with flood/spil the TK21 U covers more area than MT7 but in spot throw the MT7 is much more brighter than TK21 measured @ 250meters

In short

1. As for flood the TK21 is much brighter than LL MT7
2. In spot the MT7 ( which is quite similar to P7 ) is more brighter than TK21.

Fenix TK21 (U2) 468lm look not as bright as P7 LED lenser

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