Does Fenix advertise OTF lumens?

I just caught wind of Quark's new Turbo lights, specifically the Quark 1232 Turbo with 230 OTF Lumens. I was Just wondering ho this compares to the Fenix PD30+ with a supposed 235 lumen beam.

What would the OTF lumens be for the Fenix?

What about other big manufacturers?

Dole said:

I just caught wind of Quark's new Turbo lights, specifically the Quark 1232 Turbo with 230 OTF Lumens. I was Just wondering ho this compares to the Fenix PD30+ with a supposed 235 lumen beam.

What would the OTF lumens be for the Fenix?

What about other big manufacturers?

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IIRC, Fenix only advertises OTF lumen ratings for their tactical line of lights (TK-).

There are a few previous dicsussion along these lines around.

I suggest you use the google search for CPF only, in the top right hand corner :thumbsup:

My experience with my Quark AA2 and my Fenix L1Tv2 and E20 are that the lumen ratings for Fenix are NOT out-the-front.

For example, to my subjective perception, the low mode on my L1T (advertised @ 16L) is about the same brightness as the medium mode on my QAA2 (advertised @ 18L); the high mode on my L1T (advertised @ 98L) is about the same brightness as the high mode on my QAA2 (advertised @ 70L).

Additionally, the spill on my QAA2 is brighter than the spill area of my L1T at both these levels, as well as being a wider overall beam. Make no mistake, the Fenix's I have are good lights, but in my opinion the Quark is clearly a better overall light in terms of its beam pattern. I use my L1T as my EDC light, but am going to replace it with a QAA when they switch to the XPG emitters because from everything I've read on here those emitters produce more flood and a larger even if somewhat dimmer hotspot because of the larger die size. And, for what I use my EDC light for, flood/spill is MUCH more useful to me than throw.

The eye can't perceive difference in lumens output of 25% or so, so a difference between 70 and 98 lumens, even if measured the same way, might be difficult to perceive at best. If the hotspot and spill are larger the lumens could be the same while the spot looks dimmer--another variable to take into account.

HarveyRich said:

The eye can't perceive difference in lumens output of 25% or so, so a difference between 70 and 98 lumens, even if measured the same way, might be difficult to perceive at best. If the hotspot and spill are larger the lumens could be the same while the spot looks dimmer--another variable to take into account.

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I clearly see a difference in brightness between the two lights I mention above. As for beam size they are within 6 - 8 in. of each other so I doubt the size is responsible.

The general rule of thumb for detecting any perceptual difference is that it must be 10% or greater. Of course there are individual differences and also variation by stimulus type; going back to Stevens' Law... But the difference limen for most people is pretty sensitive.

Originally posted by B0wz3r:
The general rule of thumb for detecting any perceptual difference is that it must be 10% or greater.

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I 'm sure you are right on the two lights mentioned here, but 10% is barely visible, I suspect, except under specially controlled circumstances. The rule I've learned, here on CPF, is that a doubling of brightness is obtained by a quadrupling of lumens output--everything else held constant. Then again, everything is never constant. So, what can be perceived for a beam shot might be totally different from the light in your back yard or in a dark forest. The ambient light will also affect perception of differences in brightness----i.e. contrast effect. Small differences in lumen output will undoubtedly be easiest to perceive in a wall beam shot in a dark room. Individuals also have varying degrees of sensitivity to differences in brightness. A google search on the subject produces all kinds of research dealing with perception of brightness.


Here's an interesting thread dealing with this:
http://candlepowerforums.com/vb/showthread.php?t=168472&highlight=eye+brightness

Divide Fenix lumen ratings by 1.4 to get a close OTF number.

^

can i ask how you got the 1.4 figure?

B0wz3r said:

The general rule of thumb for detecting any perceptual difference is that it must be 10% or greater. Of course there are individual differences and also variation by stimulus type; going back to Stevens' Law... But the difference limen for most people is pretty sensitive.

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If the beam pattern is significantly different, it'll almost be next to impossible to tell which one is bright IMO.

Get a lux meter and make a lightbox, it'll work much better than our eyes.

headophile said:

i don't really pay much attention to what manufacturers have to say about how bright their flashlights are. if i'm interested in a light, i'd rather know its specifications then look for actual reviews here, especially in comparison to other lights of its class.​

my guesstimate is neither of those two could be that much brighter than the other. it just boils down to beam profile, ui, build quality, form factor and other personal preference stuff in the end.​

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i'm kinda thinking the same. the threshold for efficiency is probably not going to grow anymore.

half of me just wishes that 4sevens does the theoritical number(current * bin) just so it's easier for consumers to compare to each other since that's the industry standard. i'd rather not have a math lesson. :laughing:

HarveyRich said:

I 'm sure you are right on the two lights mentioned here, but 10% is barely visible, I suspect, except under specially controlled circumstances. The rule I've learned, here on CPF, is that a doubling of brightness is obtained by a quadrupling of lumens output--everything else held constant. Then again, everything is never constant. So, what can be perceived for a beam shot might be totally different from the light in your back yard or in a dark forest. The ambient light will also affect perception of differences in brightness----i.e. contrast effect. Small differences in lumen output will undoubtedly be easiest to perceive in a wall beam shot in a dark room. Individuals also have varying degrees of sensitivity to differences in brightness. A google search on the subject produces all kinds of research dealing with perception of brightness.


Here's an interesting thread dealing with this:
http://candlepowerforums.com/vb/showthread.php?t=168472&highlight=eye+brightness

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First, I would appreciate it if you would not tell me what my personal experience is. I clearly see a difference in the brightness of the two lights at the same time, in a variety of settings. I will be the first to admit the difference I see is small, but it is there.

With respect to my mention of the 10% change to surpass difference limen, that is the general rule for all perception, regardless of modality. Thus my mention of Stephens' Law, that all stimulus intensity/perceptual experience relationships are defined by a power function, and different sensory modalities have different average functions, and variations within a modality between types of stimuli also typically have their own unique exponent in Stephens' Law. I don't have my reference sources here in front of me so I can't state what the exponent is for brightness.

One thing that is happening here and in the other thread you reference is that the inverse square law for the diffusing of light is being confused with the non-linear relationship between stimulus intensity and perceptual magnitude; aka Stephens' Law. The inverse square law applies only to the physical stimulus, not the perception of the proximal stimulus received by an observer. So saying that perceived brightness is halved, yada yada yada is ignoring the remaining aspects of the situation in terms of what influences perceived brightness. Indeed, a highly saturated yellow light will be perceived to be brighter than a white light of equivalent lumens because of the perceptual biases that have developed in the evolution of human vision.

With respect to contrast effects, they might be a small factor at first before neural adaptation in the brain and visual system, but once that sets in (usually about 75 - 80 ms after stimulus onset) the visual system adapts and reduces the perceived contrast accordingly. This is just one instance of how the visual system and brain work, and all perceptual systems work off of ratios, relative differences, rather than absolute intensities of the physical stimulus. In the study of visual perception we refer to this as brightness constancy. There are several other forms of visual constancy, for example, color constancy; when overall levels of illumination change, there are perceptual differences that occur because of the change in the stimulus ratios yet we still see red as red, green as green, etc. This is also still true despite the reduction in illumination that results in brightness inversions of different colors (the Purkinje shift) and even when the visual system shifts from photopic vision to scotopic vision. Another example from color constancy is that if you see two objects, one red and one yellow, then you shine a green light on them, you still see them as red and yellow rather than brown and blue. The visual system adapts to the high level of medium wavelength light (green) and compensates for the presence of the green in the light.

None of what else has gone on here alters what I've already said.

-Bowser

(PhD in Perceptual and Experimental Psychology, University of California, Santa Cruz, 2005).

Edit: corrected use of the terminology, I had previously stated "Bezold-Brücke Effect". What I was actually referring to is known as the Purkinje Shift. My oversight.

berry580 said:

If the beam pattern is significantly different, it'll almost be next to impossible to tell which one is bright IMO.

Get a lux meter and make a lightbox, it'll work much better than our eyes.

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No, that's the thing that most people here don't seem to be getting that I've already stated; the beam patterns are nearly identical.

However, I see a clear but small difference in brightness between the two lights, in a variety of situations.

I lux meter/lightbox will only work better in terms of it measuring the objective stimulus strength independent of perceptual effects. It won't tell you much of anything about perceived brightness.

headophile said:

^

can i ask how you got the 1.4 figure?

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4sevens said:

*Out-the-front is the actual lumens measured out the front of the light. Not "bulb lumens," "LED manufacturer ratings," or "theoretical/wishful thinking" lumens that so many manufactures state. How does our out-the-front lumens compare? Typically, manufacturers will over-state lumens 30-40%!!! This means our lights will out perform many lights that claim 40-60% more. Our Preon I with 70 lumens out-the-front rating will outshine some lights that claim 100-112 bogus lumens. Our Preon II with 160 lumens out-the front rating will outshine 224-256 lumen lights. Just multiply our ratings by 1.4 or 1.6 on the high end. Try it for yourself! Ok, back to specifications

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This was quoted from the Preon thread in the CPFMB when 4Sevens was describing OTF lumen figures. Hope this answers a few questions.

B0wz3r said:

No, that's the thing that most people here don't seem to be getting that I've already stated; the beam patterns are nearly identical.

However, I see a clear but small difference in brightness between the two lights, in a variety of situations.

I lux meter/lightbox will only work better in terms of it measuring the objective stimulus strength independent of perceptual effects. It won't tell you much of anything about perceived brightness.

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What you dont seem to understand, its not easy to look at a beam and say that its the same beam profile. It is entirely possible that One light has SLIGHTLY more throw than another, and increases the hotspot brightness.

Its not possible for someone to objectively define in an absolute manner such small differences. You need a light meter, and either ceiling bounce, or light box because it give your hard data. Whats the use in measureing "perceived" output?


either way, I get less worked up about lumens numbers these days, more important are the tints, as long as its a decent level of light.

Crenshaw

I think OTF lumens get romanticized far too much here.

OTF lumen claims must be taken with a grain of salt as they are highly subject to manipulation.
A number of factors come into play when doing OTF testing:
>Sphere used
>Methodology and details of it's ports used or is light fully inside of sphere
>WHEN the light is tested; initial (first 30 seconds) or stabilized after X minutes - look at ANY runtime chart and you'll see the initial dropoiff as the dies get hot.
>ambient temps, added cooling, etc

So, I would be very cautious with most companies claiming OTF lumens as if it is a more 'exacting' or 'honest' number. In my opinion it has the potential to be just as much, if not more, misleading. Surefire has dealt with this well by using very conservative numbers (E2DL's were claiming 120 but testing at 160+ for example), I cannot say the same for other dealers/manufacturers.

This is why reviews that compare similar lights, a la selfbuilt's and HKJ's, are so valuable because you know you're generally looking at a fairly consistent methodology. Of course they're only looking at a single unit so they are also subject to bin variations and product 'cherry-picking'.

Crenshaw said:

What you dont seem to understand, its not easy to look at a beam and say that its the same beam profile. It is entirely possible that One light has SLIGHTLY more throw than another, and increases the hotspot brightness. Crenshaw

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Yes, it is possible. But, that is NOT what is happening here.

It is possible, even "only" perceptually, to see differences in both brightness and beam pattern as long as they are large enough. The ease with which such a distinction can be made is directly based on the size of the difference between the two stimuli. This is a basic law of all perception, Stephens' Law, as I mention above. It's one of the first things you learn about in any introductory sensory perception class; it's one of the first things I teach in the sensory perception class I teach at my university. This is a fact, not my opinion. Decades of scientific research in visual perception have repeatedly demonstrated this relationship.

The bottom line is that I see no discernible difference between the two lights in their hotspot, and a slight difference in the size of the spill beam, with the QAA2 being larger than the one from my Fenix. And, I have done this by literally placing them side by side so they are touching and projecting on an untextured, flat, white surface. And no, what I see is not because the beams are slightly offset or because I have angled them. And that is the point, I DO see a difference, despite you claiming that I don't, and also in spite of the fact that you have no idea what the content or quality of my personal perceptual experience is.

Now, my QAA2 at the advertised output of 70 lumens clearly outshines my L1Tv2 with an advertised output of 98 lumens. Again, I see this when I directly overlap their beams as closely as is physically possible. Given that my QAA2 has a larger spill beam, it is simple math to conclude that if its actual output in lumens was lower than my Fenix, then the hotspot on the QAA2 should be dimmer than that of the Fenix, but the opposite is the case. Thus, it cannot be the case that the advertised lumens for my Fenix are out the front.

Crenshaw said:

Its not possible for someone to objectively define in an absolute manner such small differences. You need a light meter, and either ceiling bounce, or light box because it give your hard data. Whats the use in measureing "perceived" output?

Crenshaw

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It is not possible for anyone to "objectively" define ANYTHING in an "absolute" manner. First, because any and all stimuli received by all the perceptual systems must be transduced through the neural receptors for that sensory modality. In vision these are rods and cones, in audition they are the hair cells in the Organ of Corti on the basilar membrane of the cochlea. (I could recite more, but I've made the point.) Because of the nature of the way neurons convert the stimulation they receive into action potentials, no perceptual system is capable in the slightest of perceiving the "absolute" intensity of any stimulus.

You are also clearly ignoring that when perceptual differences are perceived, it must be the case that the difference in the intensity of the stimuli are large enough to allow that difference to be noticed. This follows from what I've stated above on Stephens' Law. The actual "objective" amount involved is irrelevant, what is important is that the difference limen has been exceeded. Further, it's irrelevant to judging perceptual differences because the amount of "objective" difference changes as a function of the intensity of the stimuli. Stronger stimuli require larger differences for an observer to experience a perceptual difference. Weaker stimuli only need smaller changes, and this relationship is a power function... in other words, the amount of change required eventually gets too great to be possible.

Please read my post above on Stephens' Law and the perceptual difference Limen; you clearly have not bothered to do so.