P4 upgraded to Q5 not big diff???

[krazy89]

Hey Everyone,

I just swapped out the emitter on a Jetbeam MKii-X from a P4 (original) to a Q5 from DX... and there doesn't seem to be much difference at all!?!?

is it me ?!?!? unfortunately, i don't have the knowledge to take reference photos and i don't have a light meter... so it's subjective...

i also have a Dexlight... with a P4 and now when i compare the dexlight and modded mkiix... there isn't much of a difference in light?!?!?

maybe DX shipped me the wrong emitter?!?! there's no way to tell....

can you guys tell me if the difference from a P4 and a Q5 is noticeable by eye?!?!

Thanks,

KraZy

 

[WadeF]

Sometimes you can't just swap from a P4 to a Q5 and get more output. It depends on the driver, it depends on the Vf of the Q5, etc. If the driver isn't providing the Q5 with enough voltage it won't be able to draw enough current to be brighter than the P4. It may be the same brightness as the P4, but it will be more efficient and it may run longer at the same brightness. At least that is how I have been lead to understand it from reading CPF.

 

[Aussie Cheese]

the visual difference will only be noticeable at low drive currents and runtime shouldn't change unless your driver is one of constant power.

 

[krazy89]

hmm... i think the Vf of the P4 and the Q5 are pretty much the same???

as far as i understand... swapping the emitter should be an increase in light output as opposed to longer runtimes, when everything else is kept the same(ie. same driver board, as it is still putting out the same mA).... but then again... what do i know?!?!

KraZy

 

[krazy89]

quick question too... is there any way possible to tell what CREE emitter is from the ones ordered from say DX/KD???

there doesn't seem to be any markings on the emitter... or the board...???

KraZy

 

[Marduke]

It can depend on the individual Vf of the LED.

Also, can you know positively that the old emitter was a P4? Many companies spec a light as P4, and hold to that as the MINIMUM spec. These days, P4's are actually not as plentiful as you might think. A large percentage of production is now in the Q bin range. If a company wants P4's minimum, they may get an order from their supplier (Cree) which contains mostly Q2's and Q4's for example.


Edit:
Bins are not marked in any way on the LED or star. It is impossible to know exactly what bin you have received without some hefty electronics and an integrating sphere.

 

[krazy89]

Marduke...

well.. i can't be positive.. but i'm pretty sure it's not a Qx.... there's only 3 bond wires... plus it's a mkiix... so it's already like 2 generations old... so no way it can be using a Qx??!?! (can it?!?!)


KraZy

 

[Marduke]

Marduke...

well.. i can't be positive.. but i'm pretty sure it's not a Qx.... there's only 3 bond wires... plus it's a mkiix... so it's already like 2 generations old... so no way it can be using a Qx??!?! (can it?!?!)


KraZy

With 3 bond wires, it's definitely an old P4.

What you are experiencing could be one of two things (or both)

1) The new LED has a high Vf, and the driver can't keep up
2) The old "logarithmic human perception" strikes again. It takes a good 20-30% brightness increase to even really be perceived by your eyes and brain. It takes about double the brightness to be noticeably brighter.

 

[krazy89]

yeah.... too bad it's only my eyes... so it's subjective...

on top of the 2 points you pointed out.... the tint is also different from the original... it seems more cool than the original... i'm guessing that makes a difference on perceived brightness too....

dang.. i really need a light meter... know of any good cheap ones??!?!?!

KraZy

 

[WadeF]

Just to share a bit of info, when Dereelight started using Q5's they noticed there were issues with many of the Q5's having a higher Vf. Their old driver circuit wasn't cutting it so they redesigned the driver to supply the Q5's with enough voltage so they would draw enough current (1.2A) so they would outperform the previous Q4 pills. The same applies for R2's with a higher Vf.

 

[Aussie Cheese]

dx has one, i don't know how good it is, but all you really need is reproducibility and a standard, i would suggest a novatac 120 as ... 120 lumen :naughty:

 

[VegasF6]

Hey Everyone,

I just swapped out the emitter on a Jetbeam MKii-X from a P4 (original) to a Q5 from DX... and there doesn't seem to be much difference at all!?!?

is it me ?!?!? unfortunately, i don't have the knowledge to take reference photos and i don't have a light meter... so it's subjective...

i also have a Dexlight... with a P4 and now when i compare the dexlight and modded mkiix... there isn't much of a difference in light?!?!?

maybe DX shipped me the wrong emitter?!?! there's no way to tell....

can you guys tell me if the difference from a P4 and a Q5 is noticeable by eye?!?!

Thanks,

KraZy

Do you at least have a digital multi-meter? You could measure the current draw and have some idea if the Q5 is being driven hard enough. Ideally you would have measured it before and after the emitter change. Can I assume you are using a ceiling bounce method to determine brightness? I was comparing two ultrafire C3's and I couldn't hardly tell a difference looking at the beam, but if I looked down at a piece of paper the difference was more noticable.

And I thought even the old P4's had 4 bond wires? I must be mistaken about that.

 

[Marduke]

yeah.... too bad it's only my eyes... so it's subjective...

on top of the 2 points you pointed out.... the tint is also different from the original... it seems more cool than the original... i'm guessing that makes a difference on perceived brightness too....

dang.. i really need a light meter... know of any good cheap ones??!?!?!

KraZy

Yeah, tint makes a big difference

"cheap" and "good" generally don't go that well together, but I know DX has some light meters.

 

[krazy89]

haha... nova 120... if only i had that kinda money to spend....

as for the P4's... newer ones have 4 bond wires.. afaik... older ones have only 3....

as for the Vf.... i think that might be an issue... as from emitter to emitter there are differences...

as for judging the brightness... i'm tried to look at just the beam on a white wall.... can't tell too much of a diff... tried a bounce test... and to be honest.. they look pretty close.... but my eyes could just not be as sensitive to light as others... dang...

i do have a volt meter... BUT.. what do you know.. it's a friggin Fluke 12... so there's no ammeter on there... stupid... i guess i should just go buy a cheap-o-meter at canadiantire.....

as for the cheap light meter from dx... i know that i just want a delta... but it would be nice to have an accurate(or at least semi-accurate) reading....

KraZy

 

[gunga]

Take a look at the cree flux charts in this thread.

http://www.candlepowerforums.com/vb/showthread.php?t=156772


You'll see that P4 ranges from 80.6 - 87.4 lumens at 350 mA
Q5 ranges from 107 - 114 lumanes at 350 mA

You never know which P4 or Q5 you get. You also have to determine the current that the light is driving the LED.

Keep in mind that the eye is not linear in detection of brightness, so you need like 4x the lumens to notice 2x difference in brightness.

Also, Are you comparing ceiling bounce or white wall brightness? Throw? It can be hard to detect the differences. If you look at a Novatac 85 vs 120 lumens, the difference is not night and day.

Perhaps with all the Q5 hype your expectations were a bit lofty?

 

[f22shift]

you can use a manual setting on a camera

p4 to q5 on a 500ma flashlight made only a small difference when comparing pics. my eye saw no differece

 

[cdosrun]

I put Q5 binned XREs into a couple of my Fenix torches (L2D-CE and P1D-CE) and haven't really noticed any difference but I didn't take before and after photos. Still, I bought the Q5s and used a couple so I am satisfied.

Andrew

 

[Yoda4561]

Yeah cameras are sort of a ghetto lightmeter. Manually set the exposure and white balance, so that the hotspot looks "dim" on the screen and shoot a white wall. Then in photoshop or most any image viewer you can reduce the brightness on both to see if there's a real difference. The eyes love to play tricks on you. My M60 appears to have a slightly donut hole hotspot, it doesn't. The center of the beam after checking comparison pictures(and manually lowering the gamma) is noticably brighter than the rest even though it doesn't look like it in person.

 

[krazy89]

yeah.. i know the only real way to telling would be a measuring the current draw... too bad i dont' have the means to do that... yet...

as for taking photos... i have a stupid point and shoot one... no idea how to even use manual mode on it! hahah

yeah... i think you're right Gunga.... i think it is all the Q5 hype... not what it's cracked up to be....

KraZy

 

[Nake]

I too have converted one of my MKIIx to a Q5. I also have a stock one that I can visually compare it to. My Q5 is a little warmer than the P4. I can see a difference, but it's not a lot, even with ceiling bounce. Here are the readings I get with my lightbox and multimeter. Both had a 4.1V battery.

P4
1.54A
10,200 overall lux
142 lumen

Q5
1.48A
14,100 overall lux
196 lumen

Hope this helps some.