L4 Green tint - a poll

[Klaus]

[ QUOTE ]
Mr Ted Bear said:

The other thing that I wasn't too clear on was "Vf". Very simple terms.... there's only 1 pie, and no matter how you cut it, still only one... translation: the higher the Vf, the higher output (but less run time...) the lower the Vf, the lower output (but longer run time).



[/ QUOTE ]

Mmmmmhhhh,

IMO this would mean that Lumileds Datasheet is wrong - following their definition the Vf is the voltage range at which the device would generate its defined or binned luminosity at the specified max operating current - or something like that at least /ubbthreads/images/graemlins/grin.gif

This would mean that Vf would more or less translate to efficiency - now following your (or PKs ?) point the Vf would somehow mean the "overdriveability" of the parts - which was mentioned by one of our direct driving modders already but I might still voice my concern about what I believe to be a too simplistic explanation.

I think the subject would be worth some more discussion by those having handled more luxeons than I did so far.

Klaus

 

[keithhr]

Mine had a greenish hue, similar to my Spaceneedle II (seconds because of greenish hue). I called Surefire and they agreed to send me another one, So I sent it back this morning with a note. I love the beam quality and it does a nice ,short to medium range lighting job, but I wanted a white one because the greenish hue altered colors more than a bit. My Elektrolumens Blaster VI and II are stark white in contrast.

 

[Gman]

You know, it's funny. I looked at a friend's L4 the other day and it looked great. I complimented him on how lucky he was to get a white one. I was so impressed I ordered one up and was stunned to find mine was so much whiter than his. Odd, cuz I would have been completely satisfied with his had I received the same. The description of a bright vanilla is approprite to his but mine is a brillant white with the slightest blue tint. Make me wonder just how wide a range there is in these.

 

[GJW]

My two are WHITE.
Their only competition is my NexNeedle.

 

[Gman]

We've been playing with these two L4s and we noticed something. The warm vanilla one seems to show colors much brighter than the white one. The beam of the white one looks more pleasing to the eye when looked at by itself but doesn't do as nice a job on colors when shone on them. (reds and greens seem much brighter with the vanilla one.) Simply put, the vanilla does a better job of illuminating what I'm looking at though it's not as a brillant white as the other. Is this because the vanilla is closer to the spectrum of sunlight?

 

[brightnorm]

[ QUOTE ]
Klaus said:
...IMO this would mean that Lumileds Datasheet is wrong - following their definition the Vf is the voltage range at which the device would generate its defined or binned luminosity at the specified max operating current - or something like that at least /ubbthreads/images/graemlins/grin.gif

This would mean that Vf would more or less translate to efficiency - now following your (or PKs ?) point the Vf would somehow mean the "overdriveability" of the parts - which was mentioned by one of our direct driving modders already but I might still voice my concern about what I believe to be a too simplistic explanation.

I think the subject would be worth some more discussion by those having handled more luxeons than I did so far.

Klaus

[/ QUOTE ]

Klaus,

That was my original conception also, that Vf could be roughly considered as efficiency. Now I'm more confused than ever.

I would be grateful if someone could explain to me, once and for all in simple, lucid layman's terms what the darn term means. Can it really be that hard to explain to a non-rocket scientist like myself? In my field I sometimes have to explain very complex ideas, and I pride myself in making replies that almost anyone could understand. If Einstein (and some science writers) could explain Relativity clearly enough for the intelligent layman to at least begin to comprehend, can it really be true that a similarly clear explanation of Vf is so elusive?

Brightnorm

 

[Wolfen]

Mine is white.

 

[lambda]

Brightnorm

The vfd of a Luxeon does translate directly in to efficiency.

Example 1 - U3S Luxeon 5.91vfd * 700ma = 4.137 watts
Example 2 - U3W Luxeon 8.31vfd * 700ma = 5.817 watts

Both are driven at the specified 700ma max current, but the one with the higher vfd requires more energy to produce the 85 - 114 lumens specified by the U flux bin.

Lower vfd always means less power required, all other things being equall....