Luxeon bins: the differences

Hi guys,

(The straw broke the camels back in regards to LED bin differences.) This thread is open to discussion and opinions on the merits and differences in Luxeon LED's as categorized by their bin distinctions.

Vf : what is it and is it important?
Flux: Is a U bin brighter than a T bin and worth a higher price?
Tint: What is the difference between a xW0x and xY0x LED?

What is this color shift? Is it noticible?

If you have a question about bins or comments or insight regarding them, please share it here. I will be directing any questions I receive via e-mails to this thread and it may become a reasonable resource for many of us. One can hope.

Are the bin differences real? yes
Are the bin differences noticible? yes; certainly when more than one light is lit at the same time and comparisons can be made
Are superior or preferable bins worth a premium? To some, yes and to others, no.

I have currently opened my builds to some bin options which have an extra premium price attached. In some cases (U bin) I paid a premium for the LED but in others I didn't. Why the premium? Well, I already have more LED's of the selected standard bin (TY0J) prepared for mounting in the PD lights with lead wires attached than I have PD sets to host them.

Why TY0J? I feel that the TY0J when underdriven at 500 mA is closer to a tintless white and when it is well underdriven on low, it does not shift too far away from white. This is a concession for those who are after a white LED. I targeted the white at the low level as I feel that when the lights are really used, the low level is used more often than high and when using high, it is likely that more than ample illumination levels are present; color rendition is easier.

Realistically, even if a tint is obvious initially because the eye was viewing under some other source of illumination prior to a LED lighting up, in no time, the eye will adapt to a new tint and it will no longer be evident. Consider tinted sunglasses.

***************

In terms of real differences based on bin, one concept that is legitimate but not necessarily easy to grasp or quantify is that of efficacy or lumens/ watt. Efficacy is a measure of the efficiency of a LED and its conversion of energy to light. For some, only the flux or luminious output is important. For others efficiency is king. A TW0H may be a more efficent LED than a UW0L for instance but the UW0L will have a higher flux or lux measure. Another consideration for many lights is that of the fact that any inefficiency is manifest as heat. Heat can be detrimental to the well being of a LED and in fact can cause it to become less efficient; a vicious circle.

There is no free ride and as with most things, a design or selection is based on weighted compromises. The weighting can be very subjective in nature.

Do I know what I am typing about? :thinking: :shrug: At the moment, it's 2 in the morning. :green:

McGizmo said:

Vf : what is it and is it important?
Flux: Is a U bin brighter than a T bin and worth a higher price?
Tint: What is the difference between a xW0x and xY0x LED?

What is this color shift? Is it noticible?

Click to expand...

Okay, I'll take a stab.

I find that most of these staments/questions regarding the Luxeons used in our lights are based on need to have the 'best' Luxeon. The need to have the 'best' is directionally proportional to the price of the light.

Collectors and users have different views of what the 'best' may be. I consider myself a 'user' so I'll comment from that perspective.

In the case of a Luxeon on the PD platform, and in order of importance:

TINT is a big deal. Most of us will be hard pressed to tell the differences in TINT when the Luxeon is driven to spec, but when slightly underdriven, and especially when really underdriven, the TINT becomes more pronounced and the shift from 'white' more apparent. FOR ME, any tint that slides toward the blue end of the spectrum messes up my depth perception outside. Dark objects and shadows kind of meld together and I have a hard time navigating uneven terrain regardless of how long I have had the light on. Give me something with a tinge of yellow or even green in it, then I'm happy.

Vf is important because I like my light to last as long as possible without a battery change. The lower the Vf the better. Just a personal preference.

FLUX is the least important with regards to the PD platform because the light was never meant to be a hotrod. I'm not expecting to put a spot on the moon. Driven below spec, it is pretty hard for me to tell the difference between a T-bin and a U-bin unless I'm alternating between lights.
Now, as flashaholics, we all want the brightest, but I wouldn't pay a premium for a U bin in the regular PD platform, UNLESS it were of a lower Vf than the T-bin offering.
In the Ti PD, I may consider it even if it had a worse Vf than the T-bin offering. If I'm paying top dollar, I'd want the bleeding edge stuff only because it would help with the justification of the purchase in my mind.

YMMV

I guess I was one of the straws. I Emailed Don to see if he were willing to solder in a UX1J emitter from a star I bought from Fred (photofanatic) in a new PD that I wanted to order. My hope was to get a little extra light without sacrificing runtime. I guess I got a little spoiled by some of my brighter pocket lights like my HDS U60 and my Peak ranier. I would love to have a PD but the thought of it being less bright than the others is a bit bothersome to me. I have read all the points made on the practical aspects of the PD's output. But still... I guess that makes me a "light meter whore" as one PD owner has stated in another thread.
I missed out on several opportunities to acquire a U-bin Mclux III, once by a few seconds. Perhaps my reasoning is irrational; my hopes, unrealistic. Never the less, my offer still stands for Don to sell me one of his excellent flashlights with the U-bin installed. Something that to me would make this light a little bit more special.

Hey Macaw,

Everyone wants and likes a bright light. I have a few hotwires that really shine (no pun intended). However, I do find myself at times wanting a more useful light....one that doesn't blind you when you want to just find something quickly in the dark. There's nothing worse than lighting off some mega candlepower hotwire when all you want is enough useable light to find something small in a darkened room. More than once I've touched off one of my lights only to have to wait for my eye's to become accustomed to the excessive brightness.

I know, excessive brightness could be thought of by some flashaholics as sacrilege but it's true. Once you put aside your need or desire to have blinding light you can then become aware of useful light. This is something that the PD does well in spades. It took me a while to get used to the low levels of some of these EDC's, at first I thought I'd never use low level now I find it extremely useful.

Cliff

McCaw,
I have not responded to you or some others yet on requests but this is due to a glitch in the converters and their availablity. I will respond later today or tonight. I understand and agree that you guys are entitled to "have it your way". I just have to figure out how to streamline the process or pass on the expense of additional build time required. It is not a lot in the individual case but in aggregate it can be overwhelming. On a daily basis, I get E-mails that would require an hour or more (each) to answer in the detail requested. A composite for instance: "Hi, I am new to LED's and think I want a U bin with extended runtime and super bright but I am confused with the terminology and wonder about the tints. I know you don't offer it but what LED would be best and would you consider buillding this for me?"

Yesterday, I stood in line at the post office for a half hour to pick up a package that a customer had sent to me insured and signature required. My postal carrier won't bother walking back to my shop; just leaves the tag in the mail box. I know, where's that violin! :nana: Time! I need more time cause I am so good at wasting what little I have!

**********************

On another but somewhat related subject, it has been posted that there are in fact now "false jokers" coming into the population. The only way to know if a Luxeon is a joker or false joker is to know the mfg date or test it with an optic. Fun! Moving forward, the -J McR reflectors will not only work with the joker but they will be the prefered choice, IMHO, with the K2. That is if the K2 ever becomes more than vapor.

Regarding flux output. A U bin LED may not be as hot as you think.

Remember that any given Bin code has a range.

A T bin is from 67lm to 87lm.

A U bin is from 87 to 113lm.

In the worst case scenario it's possible that Don has exceptional T bins that metered 84lm and your U bin is sub par also measuring 87lm. Both LEDs would at the same current and temperature produce nearly identical light ouput. If the U bin Vf is L vs J then the U bin would be sub optimal since it would dissipate more heat and produce basically identical light output or even less with the additional heat generated.

In the ideal best case the T bin could be of type 67lm and you have a hot rod U bin at 113lm. In that case there would be larger difference and the U bin would indeed produce more light in the same environment.

Since a PD is not targeted for hot rod applications does it really make sense to put a U bin in there given the luxeon lottery? Flip a coin. You might be near the worst case or near the best case or somewhere in between. If you take the middle of the road one bin code letter is only 20% higher/lower than the next/previous. 20% increase is actually hard to see with the naked eye. Only a light meter can really measure a 20% change. The human eye is log based and a 2:1 is a typical required change for hearing, seeing on a human. Only a white wall with two lights can you see differences less than 2:1.

Let's not forget joker vs non joker. What reflector is Don using? Is it a non-joker reflector? Is the U bin a joker or non-joker? A mismatch in reflector and LED will be less than optimum in beam pattern generation.

One option that is not available is the NextgenX2 driver. It's more efficient and would perform better at higher currents than the Wiz2x2 driver. If you want brightness, you want that driver. There are issues with the configuration (can't use rechargeables) and low could be dictated by Vf below ~150mA.

This whole subject will be moot when we can get 100lm/W (~350mA) 1W White Power LEDs. Then we will be discussing the ubber-super-Kool 1/2W varieties since we would only need a 1/2W driven at 175mA to get the same brightness as we are currently getting at 500mA with the current Luxeon technology. :lolsign:. That day is approaching rapidly...

-Wayne

Of course I can't keep silent and have to add my €0.02:

IMHO the discussion of the "good" T-bin vs the "bad" U-bin is a moooot point since it is applicable for all LED bins, and with the same right you could use S-bins as they get the job done, too.

For me, the question is simple ... what difference in bin can I get for what price and what are the drawbacks, for example a higher Vin and thus reduces runtime. I always use the "average" flux per bin and for me a U-bin is brighter as a T-bin just as a T is brighter than the S.

With the current improvement of the LEDs a higher luminous flux will eventually alllow for a reduced drive current as the "target luminous flux" can now be achieved with less power (--> longer runtime, less heat, even better efficiency).

We will soon be there ... for example ... my U-bin PD is just right in brightness ... and if Don offered a V flux LuxIII ... I'd probably go for 400mA drive current. At least it is worth thinking about.


Any way ... for me, a premium LED (characteristics I want, be it flux or Vin or tint) is worth a premium price as it is a PITA to offer them. So ... I appreciate the U-bin offer very much and are willing to pay for it, but I don't require it. IMHO it is up to the builder to decide what he wants to offer, and up to the buyer if he wants to acquire the item with the offered characteristics.
Of course this is strictly a buyer-perspective, and I am a buyer who wants the best of the best within my range. I can't speak for the builder and only begin to imagine the nightmare one encounters with that binning system.
The least that can be done is a compensation for the increased workload and material in stock ... which must IMHO translate in a significantly higher price for "premium" bins offered.

bernie

This is a great thread in which I have learned a lot. Thanks guys.

Hmm, complicated thread, lots of issues.

Bins - yes they count of course, and how much is up to the user.

Flux - My personal experience is that high flux bins make a difference that matters. But, I tend to use them either at low or high rates. In the middle range, they don't matter as much to me. So, for a PD (low range) I like them.

Tint - color shift on low is up in the air for me. I have a few X1s that I can't tell from W0s, but I have one that is distinctly green on low. The theory of a Y0 having a better white on low certainly makes sense, but the Y0 tint on high is out of the "normal" range in tint for me and is subtly but pervasively annoying. W0, X0, X1 and V0 are all satisfactory to me. I'd be curious to see a V1, never have, but if I was ordering a PD today from available stock, I'd jump on the UV1J. "Normal" for me is defined as my eye doesn't seem to adjust, YA is the most obvious example of this. The critical factor seems to be, for me, the perceived color of known objects as they are lighted by a given tint bin.

Vf - not that important really to me in a regulated light, assuming something reasonable. But, in a single CR123 light, the reduced runtime with Li-Ions becomes a factor, so a lower Vf is a help, at least it makes me feel better.

Overall - assessing the individual merits of the various bin factors doesn't say anything about the total bin. Would I pay for a UYAH? No, I wouldn't want it for free, the YA makes me puke. If a high flux with my favorite tint and a low Vf came along would I want it? You betcha.

Your personal issues - I don't know how you do it. Trying to please as many customers as you must have, answering questions that in large part shouldn't even be put to you in email, the extra issues inherent in a high-end light and the customer desires this inspires, and on and on.

You where a lot of hats. Some have been put away, but some new ones have made an appearance on the rack. For everyone there comes a time to move on. What complicates things is where from you're moving. Where would you be without the place from which you're moving? What does one owe in one's mind to that place, and when is the debt paid? Or is that "all or none" thinking? A repositioning of the relationship with the original entity from which one grew mighty, may be all that's needed.

Seems to me you're on your way to a workable resolution

I don't have $.02 on me, can someone break a nickel?

But seriosly, I don't think I could add much in the way of "detail" to what has already been posted. I can add my reasoning, however, for typically choosing a U over a T. All things for the most part more easily agreed on aside (tint, Vf, etc.), I would rather pay extra to get an sub par U versus the potential of paying less to get an sub par T. I look at it as guaranteeing a minimum flux versus hoping for a maximum. But that's just me. What was it my mom always said..."Hope for the best, expect the worst."


-DF

I prefer the tint of the new nichia u-co bin emitters to YO tinted emitters. I know that sounds like a drastic statement but practical visibility of YO's (for me) is very poor. While the 5mm nichias do have a small white-blue area in the center the honey yellow area surrounding the center is the large majority of the beam and it does color and depth very well.

It took me quite a while to clearly define my preferences but I find tint bin to be much more important than brightness. I'd honestly prefer a SWO* to a UYO* any day of the week. I also prefer good x1's and v1's to YO's and XO's at least if there isn't too much green or red in them.

I do agree that for the most part being able to clearly label a tint bin requires comparison except when a person has pretty clearly identified and become familiar with the hazy, lifeless effects produced by certain bins (which may vary based on the eye). Once that effect is noticed, there is no going back and a bad tint screams bad tint everytime I use the light. I was very dissatisfied with an HDS EDC because of the tint of the emitter. If I could have changed the emitter, I would have kept it but ended up selling it at a hefty loss.

Vf : what is it and is it important?
-"Forward voltage" of the LED. The difference in runtime with the typical H-K Vfs normally available in 1 and 3 watt LEDs is negligible in my experience, and the only consideration I give it is when choosing an LED for use with a boost only circuit and Li-ion rechargeables.

Flux: Is a U bin brighter than a T bin and worth a higher price?
-It can be(certainly should be). Flux and tint vary by individual LED within and across bins. The only U bin I've used was a lottery loser in all respects, and it has jaded me about paying $30 for an LED I couldn't wait to give away. I saw a huge difference between all my S bins vs. T bins, and would expect that the potential is there for the U bin-I just haven't seen it realized yet, personally.

Tint: What is the difference between a xW0x and xY0x LED?
-A good contrast can be made using the XO, being the most neutral tint, as a standard. The WO will be "warmer", which generally means that it leans toward yellow, while YO will be "cooler" leaning towards blue. There are lots of misconceptions about tint, but think of it as looking through a pair of glasses with tinted lenses. Whatever you point the beam of your flashlight at, you overlay the item or area being viewed with the tint of the beam-like looking through glasses of that color. What happens then is that the tint contrasts with opposing colors, and cancels similar colors.
The easiest example is comparing the YA/XO/X1 bins in nature, since that gives a neutral standard, and two polar opposites.
Natural colors in the outdoors tend to be variations or mixes of yellow and green. The YA is on the blue end of the scale, and on the red side-the exact opposite of those natural colors. Because of the sharp contrast, color rendition will suffer, but details will stand out.
The XO, being mostly neutral, will give a very "normal" view, with no particular color standing out, but all being rendered accurately.
The X1, being on the yellow end of the scale, and on the green side, is closer to the actual colors of the environment and will tend to cancel those colors out, and making it harder to distinguish both color and detail.
Tint decides how you see everything you illuminate with your flashlight, and deserves some thought.


What is this color shift? Is it noticible?
-It can be. The bin code that identifies what we call "tint" is referring to exactly that. Tint. Variation from white. As the drive current falls farther below spec, the LEDs color temperature drops and it falls farther from white, meaning that the tint becomes more noticeable. Also the lesser color(the red/greens) will be more evident. For instance, a YO will shift toward green, and a VO will shift toward red.

I just made my order with Don. Because I wanted the u-bin with a low VF, I opted for the V1 tint. The YA would have been out of the question for me, I cannot stand that purple tint. looks like the V1 would do well to emulate the color of incancescent lamps which is fine by me. Thank you Don for this enlightening thread and for your adding the additional emitter options in your build thread.

A good contrast can be made using the XO, being the most neutral tint, as a standard. The WO will be "warmer", which generally means that it leans toward yellow, while YO will be "cooler" leaning towards blue.

Click to expand...

Interesting post, but to me it just goes to show, at least on a theoretical/philosophical level, how pointless it is to attempt to define tint universally. In your example, with my eyes, it would be W0 as the neutral reference, with X0 to the cool side and V0 to the warm side. Y0 is overtly blue to my eye. Some say age can effect it, with the "browning" of your lens or cornea or whatever it is. That is, the older you are the more likely you may be to prefer the "bluer" tints.

Outdoors, the warmer tints are far more pleasing to my eye. Does that mean I'm missing detail? I don't know, but at least mud looks like mud and grass looks like grass, so I know where to step. On a YA I had once, I literally couldn't tell the dirt from the grass, the "tint wash" was so strong. No LED is satisfactory for natural environment use if accurate colors are a criteria, the spectral balance just doesn't support it. How does it all work? I don't know, the brain is pretty darn complicated, but I've had every tint but V1 and WA, and the X1 is easily my favorite for a natural (green/brown) environment.

My only overall point here is that between the individual's physiology and general preferences, and the many variables involved otherwise, you can't just make reliable rules for what works. Even if there are universally agreed upon technical issues, the subjective impression of the user still must carry some weight (even if he's dead wrong )

Bob_G said:

Interesting post, but to me it just goes to show, at least on a theoretical/philosophical level, how pointless it is to attempt to define tint universally. In your example, with my eyes, it would be W0 as the neutral reference, with X0 to the cool side and V0 to the warm side. Y0 is overtly blue to my eye. Some say age can effect it, with the "browning" of your lens or cornea or whatever it is. That is, the older you are the more likely you may be to prefer the "bluer" tints.

Outdoors, the warmer tints are far more pleasing to my eye. Does that mean I'm missing detail? I don't know, but at least mud looks like mud and grass looks like grass, so I know where to step. On a YA I had once, I literally couldn't tell the dirt from the grass, the "tint wash" was so strong. No LED is satisfactory for natural environment use if accurate colors are a criteria, the spectral balance just doesn't support it. How does it all work? I don't know, the brain is pretty darn complicated, but I've had every tint but V1 and WA, and the X1 is easily my favorite for a natural (green/brown) environment.

My only overall point here is that between the individual's physiology and general preferences, and the many variables involved otherwise, you can't just make reliable rules for what works. Even if there are universally agreed upon technical issues, the subjective impression of the user still must carry some weight (even if he's dead wrong )

Click to expand...

Bob_G,
I don't know how old you are, but I'm 34 and I see things almost EXACTLY the way you do. I'm reading you last two posts and I can relate 100%! I will mention though that INDOORS (with light colored walls and carpet), the bluer tinted LEDs are fairly acceptable. I'm no scientist, I just report what I see.

Luxeon lottery aply to tint, flux and vf. You can have veriations with all three within same reel or tray of stars.

early low dome one watt luxeons as used in world's first production LED light. ARC LS first runs were greenies almost without exception. nicest samples were whitish overall with a purpleish center. if you held first run close to a white wall, you would always see green in outer edges of beam.

tint is subjective to person viewing. what I see may not be what you will perceive. luxeon tints and what bin codes are desired the most, seems to have changed. along with improvement in consistancy of luxeon production. classical example is to shine one led against wall, then watch tint change when you shine another led next to first one.

Older bining of using three digits X3T superceed to XWOT.
WO used to be the favored bin for a white tint, but it seems we've been leaning twards a blueish tint or XO tint or YO tint. this migration of tint preference has been caused in part by acceptance of multi-stage beams.

for example X1 bin luxeon when driven at spec, generally will be white. but will shift tward greenish when under-driven. again this depends upon luxeon lottery.

early Ubins displayed the widest veriation within same bin code of any recent luxeon. this aplies to all flux, tint and vf. I've noticed very few exceptional high flux Ubins. VS a larger number of exceptional Tbins.

mutant LED's do apear from time to time. most famous example is ARC4X. emitters was vetted from production, some out of reels of P flux emitters. there were aprox. 6 ARC4X produced. I've discovered ONE early ARC LS first run #1003 with output equal to most Tbins. that's not impressive until you realize this light was produced very early in history of Luxeon lights.

another example would be Xbin run of MRX-X3T by hotbeam (aprox 12 produced). I suspect some of those may be Ybin, as reports of several MRX putting out flux equal or greater than Surefire M6 with LOLA.

the fab L1-PR-T 917 built by Don used overachieving emitters that easily put out flux equal to Ubins.

one watt luxeons are rated at 350 milliamps VS 3watt luxeon are rated at 700 milliamps. if you read spec sheet both are are rated at temp's not possible to maintain within a light past a minute or so.

junction temperture of luxeon die will increase imediately as luxeon lights. this will lead to flux reduction as emitter heats up. if a light is designed with good thermo path, expect at least a 20-25% reduction in flux. hand held lights have advantage of hand's natural radiator effect.

it's generally not a good idea to do unattended runtime tests with overdriven LED lights without thermo protection. emitter could cook to death.

Tint: Simple Equation...
If Overdriving(1 to 1.2 A) .. use Bins that are above WO in the BBL ... example V1 & X1....
If Under driving (350 - 500mA).. use bins that are below WO in BBL ... example YO & YA

If Driving at spec (around 600 - 800 mA) use bins as desired.

However simple it sounds, but it's not completely true, one should take care of NON ideal situation, like Actual Operating Die Temprature (WHEN LIGHT IS HELD IN HAND) and not stable 'ideal' Laboratory conditions... with loads of measuring instruments .. tint shift's is a function of Current, Vf(variations) AND Junction Temprature

For Vf AND Flux, Lower, the better in it's class. (more efficient will be the ones which have lower Vf).

For driving at 500 mA I would prefer UYAH .... for driving at 1A I would prefer UV1H .. (wonder if these bins are available).. this will eliminate use of Premium Tint

But since U bin's are not that cost effective.... (costing above $30) mostly... Choosing any thing other than TXOH, TWOH would do... all that is required is to drive the LED's at appropriate currents. One can Overdrive a TX1J (at about 900mA to 1A) to obtain effect of UXOK at 700 mA in normal operating conditions.

Great dialogue here guys! :thumbsup:

If a newbie comes here and looks at the Planckian graph provided by Owen they will say, "Where's the white?!?!?" BTW, did that graph get toned down from its initial posting?!?! If not, then my PC and laptop show that graph in a very different light!

Individual spectral sensitivity and response as well as color and hue contrast in the the viewed landscape can bias ones perception and determination of tint preference in a LED. It could well change from one scene to another if a person were open to re evaluation. The preference is subjective and probably objective at a personal level which will vary from person to person. Why do we not all share a favorite color? :thinking:

As pointed out already, within a single bin rating, one can find obvious variation. The UX1x's I have built with can be what I consider to be warm or cool in tint and hardly seem appropriate to be binned, by tint, in the same class.

The LED's can often give a greenish tint and this is very distinct and noticible relative to experience with incandescent sources and certainly in the ambient presence of incan lighting. This difference was initially noted early on with the Luxeons and terms like cat pee green were coined. (Is cat pee green? I never looked.) Green got a bad rap, by and large, IMHO, because it was different!! Different, yes. Most interesting to me is the fact that it was new! If you look at a spectral graph of color temperature based on a black body emitter, there is no green anywhere in the spectrum!! LED lights are missing power and emissions in the red end of the spectrum and suffer as a result, to an extent. An incan is typically missing power in the blue end. I ramble but the point I think I am trying to make is that LED's bring a new and different light to bear. Perhaps this is why I find I prefer the YA bin when looking at the beam and not what the beam is illuminating; a refreshing (to me) and distinct new outlook and sight.

Now tint is about color and color can be used to differentiate and identify objects within the field of view. Contrast in intensity can be even more important in low levels of light than color and we often can have enough information with a monochromatic view with no color information what so ever. If we identify the object as grass, is it critical that we know what color it would be under a noon sun with a blue sky? I am satisfied with the knowledge that it is grass. Under a bright noon sun with blue skies, I might well alter my perception with tinted sunglasses anyways.

Back to the grass. I have read articles and discussions on landscape illumination and the concensus points to using white to blue white light for illumination of landscape in lieu of warmer and yellowis light because the warmer tints will make the foliage look brownish and unhealthy. Landscape lighting is for the most part intended to provide a pleasing and healthy view; not necessarily the greatest level of contrast and means of object identification.

In the image below, I think the same information is available yet the colors are not the same. One view is likely more pleasant to the viewer than the other.



Below and on the left is the image you would likely see under the ambient conditions and on the right is what I would prefer to see.



In all four images, I can get the same amount of information. Now if I were a marine bioigist, I might have a different take.

We look to see and see to identify and understand our surrounds. In the absense of sufficient ambient light, we bring our own light to bear. Sufficient and appropriate illumination in our hands will provide more information than we really need. If we want to enhance what we see, and enjoy the image, we may choose to tint the image with a preference towards color. If we have insufficient light in hand, we may opt to forego that which is pleasant for that which is informative. A blind man can navigate in a scene which we may choose to illuminate. We have choices and preferences we can employ. Some choices may make the scene more pleasant to our eyes and some may bring out more detail and information. These choices may not be the same.

We shouldn't discount the complexity of human visual perception nor should we assume that we share the same abilities and levels of intensity in perceptions. There is an underlying need to know that may not parallel a want to know; a view through rose tinted glasses or via a YA bin emitter. :nana:

Offering a bin option in a light build or chosing to modify a light with an exchange of LED based on bin is an option available in some cases and at some expense. As most options go, the driving force may be want more than need and it is possibly useful to be aware of the distinction. Then again for many of is want actually is perceived as need!

Vf and Flux are best illustrated with graphs and numbers and charts which are never in view when you are actually using a light. They do have their bearing to be sure but within practical applications and usage of a light, to what absolute or objective measure do they count? :shrug:

Can anyone provide a reasonable for instance where a LED of bin alpha will succeed at a task and a LED of bin Beta would fail? Don't get me wrong here. There are definitely better bins and worse bins. My personal grading of better and worse may not agree with yours nor may the significance of better to worse agree. If your example is taken at a limit or margin then I am likely to grant your example as legitimate but not necessarily reasonable.

Thanks Don for starting this valuable thread with its detailed discussions of bin questions that have puzzled/confused many a CPFer, myself included.

I think it should be stickied.

Brightnorm