Can anyone explain this statement:

[leon2245]

(light x) has a beautiful and very uniform output, but (light y) has slightly "more perfect" diffusion.

^Is it even possible for that statement to be true (I thought the better the diffusion the more uniform the output)?

 

[mvyrmnd]

If they're talking about the same emitter, probably not.

If they're comparing different emitters then possibly but
<RANT> THEY SHOULD BLOODY WELL LEARN THAT R2 AND R4 ARE FLUX BINS AND NOT EMITTER NAMES!</RANT>

grr....

 

[tam17]

R2 and R4 are flux bins, really nothing to do with diffusion and uniformity.

Perhaps the reviewer noticed the lumen and tint differences between two particular XP-E R2 and R4 emitters and misinterpreted them as uniformity/diffusion :confused:

AFAIK all E05 TIRs w/diffusers have the same geometry regardless of emitter flux bin, so how come the uniformity/diffusion difference?

BTW you should have told us that this talk is about E05 :shakehead.

Cheers,

Tam

 

[leon2245]

Let's put aside for the moment which flashlight, & the reviewer's use of r2/r4, and just say we're comparing two completely different hypothetical flashlights. I'm more curious about the terms "diffusion" & "uniformity", & whether the statement about one having better uniformity & the other better diffusion as if they are mutually exlcusive characteristics is even possible in general. Because it seems like perfect diffusion would be perfectly uniform. If not, can someone explain the difference?

Thanks for the feedback!

 

[mvyrmnd]

Now that you've explained a little more than the original, rather vague, quote, I can think a little more. A light can be more diffuse and less uniform, as well as less diffuse and more uniform. They are different entities, to me. Uniformity would apply as much to a highly focused beam just as much as it would apply to a diffused beam.

 

[woodentsick]

I think he means that while the 'R2' has a uniform output, the 'R4' projects light over a greater area (i.e. floodier). Or, maybe he means the R4 has an even more uniform beam than the R2.

 

[Foxfyre]

Diffusion is defined as scattering as in a flood pattern, the opposite of a spot or tightly focused beam. Uniformity refers to the evenness of the light pattern.

A uniform flood would appear as a smooth even pattern of light where a non uniform one would have brighter and dimmer places, or "artifacts" in it.

A uniform spot would be tight and evenly lit where a non uniform one would be misshapen, have uneven edges or bright places off center in the projected beam.

I hope this helps. If someone can make it clearer or if I have something wrong please correct me.

 

[shao.fu.tzer]

Diffusion is defined as scattering as in a flood pattern, the opposite of a spot or tightly focused beam. Uniformity refers to the evenness of the light pattern.

A uniform flood would appear as a smooth even pattern of light where a non uniform one would have brighter and dimmer places, or "artifacts" in it.

A uniform spot would be tight and evenly lit where a non uniform one wouls be misshapen, have uneven edges or bright places off center in the projected beam.

I hope this helps. If someone can make it clearer or if I have something wrong please correct me.

Nope... that sounds right... You beat me to it... I was basically going to post the same thing. That being said, a diffuser can make a less uniform beam much more uniform (IE - eliminating reflector artifacts, bypassing bezel crenelation artifacts, eliminating Cree rings, correcting off-center emitter splash). So... make of it what you will...

 

[tam17]

I'm not a native English speaker (obviously the finesse is missing), but I fully agree with foxfyre's definitions :thumbsup:

Take LD15 as an example: it has a diffuse but not uniform beam.

Cheers,

Tam

 

[leon2245]

Diffusion is defined as scattering as in a flood pattern, the opposite of a spot or tightly focused beam. Uniformity refers to the evenness of the light pattern.

A uniform flood would appear as a smooth even pattern of light where a non uniform one would have brighter and dimmer places, or "artifacts" in it.

A uniform spot would be tight and evenly lit where a non uniform one wouls be misshapen, have uneven edges or bright places off center in the projected beam.

I hope this helps. If someone can make it clearer or if I have something wrong please correct me.

Thank you, I knew I had to be missing something between those two terms, but understand the distinction perfectly now. And with that am pretty sure to what he's referring specifically after having compared notes from our review threads. Appreciate it Foxfyre, & everyone!


lovecpf

 

[kramer5150]

A statement made by someone who is confusing flux BIN with emitter model number.

According to the CREE datasheet, the XPE is not available in an R4 BIN. So by that "hidden" piece of data, an R4 would HAVE to be an XPG. However the XPG is available in an R2 BIN... so... well, you know.

 

[Th232]

Actually, there are now XP-Es in R4, although they're quite recent:
http://www.cutter.com.au/proddetail.php?prod=cut1214

 

[leon2245]

Okay hopefully it's not too conceptual now, but I've since edited the quoted review statement by replacing his (misused) terms with hypothetical flashlights.

 

[robostudent5000]

I think he means that... the 'R2' has a uniform output, (and) the 'R4' projects light over a greater area.

i agree with this. the "but" in the original sentence probably should have been an "and". he probably wasn't trying to say that the R4's beam pattern is not uniform. he was probably trying to say that the R2 has a uniform beam pattern and that the R4 is floodier while not excluding the fact that the R4's beam pattern is just as uniform.

AFAIK all E05 TIRs w/diffusers have the same geometry regardless of emitter flux bin, so how come the uniformity/diffusion difference?

the TIR may be the same, but the Xp-e has a 115 degree viewing angle and Xp-g has a 125 degree viewing angle. the Xp-g's wider viewing angle and larger emitting surface creates a wider beam.

 

[kramer5150]

That makes even less sense now than it did before... IE, that statement does not mean anything to me.

 

[StarHalo]

Uniform output:

 

[leon2245]

what does uniform output mean anyways?

lol I know, right? It didn't make sense to me either, until Foxfyre explained the distinction:

Diffusion is defined as scattering as in a flood pattern, the opposite of a spot or tightly focused beam. Uniformity refers to the evenness of the light pattern.

A uniform flood would appear as a smooth even pattern of light where a non uniform one would have brighter and dimmer places, or "artifacts" in it.

A uniform spot would be tight and evenly lit where a non uniform one wouls be misshapen, have uneven edges or bright places off center in the projected beam.

:thumbsup:

 

[beerwax]

an xpe r2 has does have a beautiful and uniform output. and is often called an 'r2' which i know upsets some people but in the current time period when talking flashlights an r2 is gunna be an xpe.

there is now an r3 and an r4 and i am curious how they compare to my much loved r2s. i think the writer is saying the diffusion is even less irregular, which might be a reflection of reflector difference, or not , as it is possible that intensity across the die varies or the die is more perfect or other factors that folks that know more than me can understand.

either way it is a positive comment on both leds , and i absolutely reserve the right to make statments that make no sense. at least to any one else.

cheers

 

[Foxfyre]

Reading the beautiful and uniform output line again just added another possible interpretation in my mind.

I wonder if the reviewer could be also referring to color and pattern of the beam (such as a flood with a brighter spot in the center of the pattern) and the steadiness of the lights output level (no flickering or PWM).

I agree with beerwax about the diffusion being more even giving a cleaner and less artifact filled light pattern.

Perhaps I'm overthinking this.:duh2:

 

[shao.fu.tzer]

Uniform output:

I wonder if he wears that getup for safety while biking at night... I would think it would have the opposite effect. I imagine drunk drivers everywhere would instinctively drive into him, thinking him to be a liquor store.