Lux readings are overrated

[orbital]

+

Sure there needs to be an objective measurement in lights, so are we giving too much emphasis on Lux?
It's measuring the intensity of a beam, and to increase its Lux, you increase forward current & focus.

Is a light with a higher Lux number better?,....I say not really.

Some of the most useful beams are from a slightly floody SSC beam profile, and that same useful beam would give a lower Lux.

Are Lux readings becoming an overrated value?

 

[Bullzeyebill]

+

Sure there needs to be an objective measurement in lights, so are we giving too much emphasis on Lux?
It's measuring the intensity of a beam, and to increase its Lux, you increase forward current & focus (i.e. throwers)

Does a light with a higher Lux reading win?,....I say not really.

Some of the most useful real world use beams are from a slightly floody SSC beam profile, and that same useful beam would give a lower Lux.

Are Lux readings becoming an overrated value?

Lux readings are what they are. Just information, and only information about a given light and its reflector, or optic, or no optic reflector and the LED that provides the light. Increase the output and lux will go up, decrease output and lux will go down, for that same light. Does not tell anything about overall output.

Want measurement for total light output then use some sort of measuring device such as a homemade light box or sphere, or do simple bounce with a lightmeter for comparative purposes.

Yes, a floodier beam might be the more useful beam than a sharply defined high lux beam, or the other way around, depending on the circumstances and an individuals preference

No, lux is probably not overrated, and lumens are not overrated either. Just information. You get to make the choice, and you can have it both ways. A high lumen floody light with awesome lux, just add horsepower to that Seoul P4 with the right reflector or optic.

Bill

 

[KeyGrip]

Are Lux readings becoming an overrated value?

I think all output ratings are over emphasized when choosing a light. They are important factors to keep in mind, but getting an accurate output rating is difficult. I sometimes see people choosing one light over another based on an output difference that is not visible to the human eye.

 

[dulridge]

+Sure there needs to be an objective measurement in lights, so are we giving too much emphasis on Lux?

If I could only have one piece of information, I'd probably choose peak lux over beamshots of a single light which give no information about relative brightness. This is assuming that the light is a "normal" light, i.e., not a "thrower" or a "flooder" specifically. It is safe to assume that a "normal" light will emit a beam of 6-15 degrees and a normal distribution of light outside the hotspot. Given that far more information than that is usually given, it is not an issue.

I sort of agree with your argument but if it came down to a single piece of information about a light, lux at a given distance (or lumens come to that) is one of the more useful pieces.

 

[Jay T]

I feel that the 1 meter lux rating is way over rated. The main thing being tested is focus. If you were to take two lights with the exact same lumen output. Light A having a hot spot 3 inches in diameter and light B having a hot spot 6 inches in diameter, a difference of only a few degrees. Remembering your basic geometry tells you that light B has it's light spread over an area four times as large as light A. Light B's lux reading would only be 1/4 of Light A. The masses at CPF would scream "Light A kicks butt!"

Now take Light B and double it's output, light A would still beat it and the masses would scream "Light B sux!"

Another problem is that people take these reading as an absolute and compare reading from different users. Problem is not all meters are the same. I own two and I just compared them both using the same light, one read 5,300 and the other 6,000. A difference of about 15% with the same light.

Why the difference? I'll take a wild guess and say that it's because light meters are designed to read the ambient light level hence they have a dome to scan 180 degrees. We are shinning beams straight at em, not what they were designed to do.

I have posted a couple of reviews where I used my light meter in either a lightbox or for a bathroom ceiling bounce to compare several lights together. I also posted controlled beam shots showing the shape of each lights beam allowing one to see if the light was a thrower or a flooder.

 

[SilverFox]

Hello Jay,

The dome on the light meter provides some measure of cosine correction. The meters are designed to have the light source precisely in line with the sensor. Without the cosine correction dome, you would have to factor in any deviation from being perfectly lined up. The dome allows you to be slightly off and still get accurate readings.

Tom

 

[SilverFox]

Hello Orbital,

Illumination measurements are one piece of the description of a beam of light. I think the problem comes because most people don't know how to use this information, or just what it means.

For example in this post, I gave a description of the illumination from two different lights. I also added that the "hot spot" of the beam was large enough to entirely cover a 3' x 3' table top, indicating that both lights were basically all flood.

If you have a meter to read illumination, you can take my information and test your lights to see how they compare, and establish how much light you need to handle your detailed work.

In this case, I was looking at close up illumination. When we consider distant illumination, things can get a little more complex. The distances may be variable, and the size of the objects we are trying to illuminate may vary as well.

I think Doug (Quickbeam) did a very good job of providing enough information to understand what you can expect from the beam of a light. He provided lux, an attempt at total output, and a beam shot on a target showing the size of the hot spot, the intensity of the hot spot relative to the spill light, and the overall size of the total beam.

His review information provides enough information to determine how far the beam will "throw," how large the total beam will be at various distances, how large the hot spot will be at various distances, and a reasonable indication of the relation of spill to hot spot brightness. Add to this the overall output reading and we have an estimate of total lumens. Throw in a runtime chart and we have a very good idea of what this light can do.

I think that lux measurements are very important if your goal is to illuminate something at some distance from you. While it is only one piece of the information you need to understand the beam, it is a very important piece.

I think that lumen measurements are the ones that are over rated. I don't really care how many lumens a light is capable of, as long as it gives me a smooth hot spot of around 1 meter in diameter, gives me 200 - 600 lux within that hot spot at around 10 meters, and has a spill that is evenly tapered from the hot spot and has an illumination that is about 3 stops down from the hot spot illumination. With a hot spot reading of 600 lux, a 3 stop reduction for the spill light would put it at around 75 lux.

I have no idea of how many lumens it takes to produce a beam like this, but if handed a light I can quickly measure out 10 meters, set up my lux meter and take some measurements.

As you can see, I place my value on the performance of the light. If you tell me that your car has XXX horsepower, I will find that interesting, but if you tell me that you have your car set up perfectly and it is capable of doing the quarter mile in 4 seconds, you have my total attention. While not a perfect analogy, I look at lumens in the same way that I look at horsepower, and lux in the same way that I look at quarter mile times.

Tom

 

[Bullzeyebill]

Tom, not being picky, but I want that 60,000 lux at one meter light of yours. Use inverse square law. I am usually content with 5,000 lux outside though my 42,000 lux (one meter) VIP with 3" reflector (BBH), running one amp to led and a Seoul P4, is plenty good too.

I concur, particularly for outside purposes, that a nice big hot spot fading to a fairly high lux flood is ideal, except where a bright flood might give glaring backspill. Inside I am thinking more flood is better than a bright hot spot, so KL4 works nicely and the tower led module in my E1E is ok too.

Bill

 

[SilverFox]

Hello Bill,

... You did notice that I gave a range didn't you... Oops, I guess I just picked the high end of the range for my hot spot example.

Actually, the X990 exceeds that in the hot spot by quite a bit. At 10 meters mine is at around 2700 lux, which normalizes to around 270000 lux at 1 meter. I have my beam adjusted somewhere between spot and flood in an effort to give me a large hot spot.

A contrast to this is the MagCharger. It puts out a very intense bright hot spot, but has minimal spill. If the object you are trying to illuminate is only a few inches in diameter, the MagCharger, at its tightest focus, would be a very good choice.

Tom

 

[Bullzeyebill]

Tom, right, tight pencil beams don't afford much advantage at distance, unless you are using binoculars. I too like a wide high lux beam for distance, something that most LED lights don't offer.

Bill

 

[Nitro]

Are Lux readings becoming an overrated value?

Not if you want Throw, which some do.

 

[orbital]

+

Thanks Tom for the informative and well written posts.

Looking at my own lights, I'v adjusted the beams so they are all slightly different (right tool for the job),
with slightly floddy beam patterns most useful; i.e. P60 SSC drop-in.
I personally like the bounce test to gauge my lights output.

Also, thanks for referencing Doug at Flashlight Reviews, gotta give him credit for getting me started in all this!..:thumbsup: