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  1. #1
    swag ho Administrator
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    Is a lumen a lumen?

    What is a lumen? Where do all these lumen figures come from?

    Did someone actually measure the light output of all these production lights? Or are manufacturers just estimating their lumen output from bulb ratings?

    How accurate are the manufacturer lumen ratings? Is there any way to verify them? Is a 500 lumen HID light the same brightness as a 500 lumen LED light?

    Enquiring minds want to know. I'm observing that 3 different '500' lumen lights seem to have noticeably different output levels.

    fc
    IPA will save America

  2. #2
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    A lumen is a lumen. That being said, however, most of the ratings are best case scenarios and don't take into account losses in the lenses, reflectors, etc. The only company that I says how they measure the output is NiteRider on the TriNewt. They state in the paperwork that comes with the light that they used an integrating sphere -- the only method that I am aware of -- to measure the output in lumens.

    Princeton Tec might also... I remember having a discussion like this with them, but my memory is a wee bit foggy on the details at the moment.

    If any other company does this, I'd like to know.

  3. #3
    Enlightened
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    As far as I know, yup, a lumen is a lumen is a lumen.

    Companies are out there to deliberately mislead consumers by tricking consumers into thinking that they are getting more utility than is the case. Look around and you'll see them... peak power on sound amplifiers, non-SAE horsepower ratings, contains real fruit, etc. I put turnkey lights with bulb lumen ratings into this general rubric.

    The use of an integrating sphere implies to me that the lumens made by the torch has been measured.

    Think of bulb lumens as the gross amount of light and torch lumens as the net amount of light after incidental losses due to design. Efficiency is a big deal when one doesn't have much light to play with.

    Flashlight wise, SureFire has been rating with torch lumens for a while now.

    Beam pattern, colour temperature, environmental factors, viewer night vision accomodation can all play a part in perceived light values. Integrating sphere output is not subject to interpretation but I suppose if it was not built properly then the results could be skewed?

  4. #4
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    Quote Originally Posted by mudmojo

    Beam pattern, colour temperature, environmental factors, viewer night vision accomodation can all play a part in perceived light values. Integrating sphere output is not subject to interpretation but I suppose if it was not built properly then the results could be skewed?
    You eluded to an important point, but didn't hit is head on. Color Rendering Index (CRI) plays a huge role in perceived brightness because it takes into account the distribution of light out put (the total color spectrum). Color rendering index is important because a large part of how we identify objects is by color. This is different than color temperature. Color temperature is a measure of the total sum of output of a white light source, while CRI takes into account the actual distribution of light colors.

    To give you an example the sun has a color temperature of 6500k, and a CRI of 100 during the middle of the day. An incandescent lamp has a color temp of about 3000k, while an HID has a temp of about 4200k. This causes most people to say, oh an HID is much better, its color temp is closer to natural sunlight. When they make this conclusion they are far from correct. When you look at a HID's CRI, you find it is a low mid 70s, while the incandescent bulb is in the high 90's. This is why even though HID's are bright, objects tend to look flat. LED's suffer from a low CRI index also, but they are getting better each generation.

    http://www.gelighting.com/na/busines..._rendering.htm
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  5. #5
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    Lumens is a measure of all the light from a source that is in the visible range by the human eye, weighted by how sensitive a "standard human eye" is to the different colours. It's not perfect, but it's a repeatable measurement.

    I doubt all light manufacturers measure their lights, but some certainly do. However, like all specs that get reported, they are often under ideal conditions, or quoted as a theoretical maximum. LED's an bulbs vary greatly from one to another, and lumens output decreases over their lifetime

    An integrating sphere is the best way to capture all the light from a source, but you still have to analyze the spectrum. A band pass filter can be used, but they are not that accurate for lumens determination. An HID puts out alot of energy in IR and UV, which we cannot see (but the sensors can), so that has to be removed from the measurement. White LEDs produce no IR or UV (they are essentially a blue LED and a Yellow phosphor). This is why digital cameras often show HID's or Halogens (lots of IR) as brighter than LEDs when they look the same in person. Also your eyes are probably not the same as the "standard eye" and depending on the colours that are emitted from a light, it may seem to have a different brightness than someone else.

    Objects can also visibly fluoresce when UV light hits them, so sometimes things look brighter with a HID because some of the UV is being converted to visible as it is reflected back.

    Our eyes are also logarithmic with intensity, so a change from 100lm to 200lm appears as a much larger change than one from 400lm to 500lm. (I should be using lux, but let's not confuse things more).

    Then there is the age thing, some of our older riders can't get by with as little light as some of the wippersnappers. Heck, there are a lot of young riders that can't stand riding with anything less than an HID (or 2!) when a lot of us ride happily with 100lm~200lm.

  6. #6
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    Ahh yes. I recall reading an article on automotive halogen versus HID headlamps.

    For what it was worth, the study showed that objects being illuminated by halogen light were more successfully identified. HID's did not lend to object recognition as well as everybody had thought. So one can look at objects better but not necessarily see objects better.

    However if one is jamming along singletrack at midnight, one might not care too much for identifying that slug... or wait, is that a snail?... by the side of the trail.

    I absolutely could not wrap my head around this until I started playing with coloured LED's and a ride in my friend's E46 M3 with what I reckon were badly colour shifted capsules.

  7. #7
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    From my time spent on the CandlePower Forums, this topic gets discussed in detail. The lumens figures are from the emitter maker, and is measured at the emitter surface. As stated by James above, loss from lens / reflector, etc. is not measured. Therefore real world figures are tough to obtain. On occasion, one of the geeks on CPF with a integrating sphere will test an MTB light, but they are often homemade. There are quite a few flashlight tests, and one can get a feel of mfg lumen best case figures vs real world lumens.

    That is why you do light shootout tests for the rest of us geeks.
    Plus James' invaluable reviews, and so on.
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  8. #8
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    Speaking of colour, I have a question to complicate things.

    I was talking about lighting to a boatsman friend of mine. He indicated to me that on the boat at night he uses red lights exclusively. He said that the reason for this is red doesn't desensitize your eyes to ambient light. So, for instance, if you are reading a map to red light, you still retain your night vision for viewing areas which aren't illuminated. So I was wondering if red headlights would be better than white? I've never tried it. I was just wondering.

  9. #9
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    Quote Originally Posted by Cino
    Speaking of colour, I have a question to complicate things.

    I was talking about lighting to a boatsman friend of mine. He indicated to me that on the boat at night he uses red lights exclusively. He said that the reason for this is red doesn't desensitize your eyes to ambient light. So, for instance, if you are reading a map to red light, you still retain your night vision for viewing areas which aren't illuminated. So I was wondering if red headlights would be better than white? I've never tried it. I was just wondering.
    I think using red headlights would make it harder to distinguish between some objects as a limited range of colours would be represented. This might be okay for walking and is definitely fine for reading, but I wouldn't really want to try it when moving at speed.

  10. #10
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    Quote Originally Posted by Cino
    I was talking about lighting to a boatsman friend of mine. He indicated to me that on the boat at night he uses red lights exclusively. He said that the reason for this is red doesn't desensitize your eyes to ambient light. So, for instance, if you are reading a map to red light, you still retain your night vision for viewing areas which aren't illuminated. So I was wondering if red headlights would be better than white? I've never tried it. I was just wondering.
    Short answer is no.

    The use of red lights for night time navigation & astronomy is to preserve your night vision. Your eyes have 2 types of sensors, cones which are used for colour and detail, rods which are used for low light. In low light conditions, your rods will migrate to the front of the retina to serve duty, which take about 20 min. If you turn on a white light flash light, your retina will return to using the rods, and you loose your night vision - which take a while to return. Red light, as long as it is not too bright, will not cause your rods to activate, preserving your night vision.

    Night vision has no colour sensitivity (you see in B&W) and has poor resolution. As a result, bike lights (like automobile lights) are bright, and designed to work with your day vision.

    Under a bright moon, you can try riding with your night vision by turning off your lights, and waiting for your eyes to adjust. You cannot tell colour, and detail is hard to discern, so you learn to let the bike flow. It's different, some of us find it fun, but it's not for everyone.

  11. #11
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    And here I thought I was a light geek

  12. #12
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    Quote Originally Posted by Flyer
    And here I thought I was a light geek
    you've just got expensive tastes and most likely wear your dark tints during glow riding

  13. #13
    swag ho Administrator
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    Thank you, thank you for the responses so far. They are most helpful and will guide me when talking to the manufacturers. It does look like Lumens is a 'claimed output' spec with no measurements performed (except for Niterider).

    I'm playing with 19 lights right now. Here's a taste of some highlights.

    fc
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  14. #14
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    Quote Originally Posted by francois
    Thank you, thank you for the responses so far. They are most helpful and will guide me when talking to the manufacturers. It does look like Lumens is a 'claimed output' spec with no measurements performed (except for Niterider).

    I'm playing with 19 lights right now. Here's a taste of some highlights.

    fc
    you're a bit of a tease

    at least give us a list of the lights

  15. #15
    Spanish biker
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    Quote Originally Posted by All Mountain
    you're a bit of a tease

    at least give us a list of the lights


    Greetings - Saludos

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    Warning!!! my english is very very bad, sorry.

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  16. #16
    Nightriding rules SuperModerator
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    Quote Originally Posted by All Mountain
    you're a bit of a tease

    at least give us a list of the lights
    totally.... Francois.... spill the beans

  17. #17
    swag ho Administrator
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    [SIZE=2]
    Quote Originally Posted by All Mountain
    you're a bit of a tease

    at least give us a list of the lights
    [/SIZE]
    [SIZE=2]Light[/SIZE] [SIZE=2]Price[/SIZE]
    [SIZE=2]Ayup bar (regular kit)[/SIZE] [SIZE=2] $ 380.00 [/SIZE]
    [SIZE=2]Ayup helmet[/SIZE] [SIZE=2]
    [/SIZE]
    [SIZE=2]BR Lights Jeni H[/SIZE] [SIZE=2] $ 299.00 [/SIZE]
    [SIZE=2]BR Lights C2.1H[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Cateye Tripleshot[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Dinotte 200L [/SIZE] [SIZE=2] $ 249.00 [/SIZE]
    [SIZE=2]Dinotte 200L Dual[/SIZE] [SIZE=2] $ 349.00 [/SIZE]
    [SIZE=2]Dinotte 600-LI-4C[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Exposure Enduro Maxx[/SIZE] [SIZE=2] $ 450.00 [/SIZE]
    [SIZE=2]Exposure Joystick Maxx[/SIZE] [SIZE=2] $ 250.00 [/SIZE]
    [SIZE=2]Jet Lites Shadow Lithium[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]Knog 605[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Light and Motion Vega[/SIZE] [SIZE=2] $ 175.00 [/SIZE]
    [SIZE=2]Levin Brightstar[/SIZE] [SIZE=2] $ 270.00 [/SIZE]
    [SIZE=2]Light and Motion Stella 180L[/SIZE] [SIZE=2] $ 300.00 [/SIZE]
    [SIZE=2]Light On Expedition 1000[/SIZE] [SIZE=2] $ 800.00 [/SIZE]
    [SIZE=2]Lupine Betty 12[/SIZE] [SIZE=2] $ 1,185.00 [/SIZE]
    [SIZE=2]Niterider Minewt.X2[/SIZE] [SIZE=2] $ 190.00 [/SIZE]
    [SIZE=2]Niterider Trinewt[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]
    [/SIZE]
    IPA will save America

  18. #18
    Nightriding rules SuperModerator
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    Quote Originally Posted by francois
    [SIZE=2]
    [/SIZE]
    [SIZE=2]Light[/SIZE] [SIZE=2]Price[/SIZE]
    [SIZE=2]Ayup bar (regular kit)[/SIZE] [SIZE=2] $ 380.00 [/SIZE]
    [SIZE=2]Ayup helmet[/SIZE] [SIZE=2]
    [/SIZE]
    [SIZE=2]BR Lights Jeni H[/SIZE] [SIZE=2] $ 299.00 [/SIZE]
    [SIZE=2]BR Lights C2.1H[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Cateye Tripleshot[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Dinotte 200L [/SIZE] [SIZE=2] $ 249.00 [/SIZE]
    [SIZE=2]Dinotte 200L Dual[/SIZE] [SIZE=2] $ 349.00 [/SIZE]
    [SIZE=2]Dinotte 600-LI-4C[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Exposure Enduro Maxx[/SIZE] [SIZE=2] $ 450.00 [/SIZE]
    [SIZE=2]Exposure Joystick Maxx[/SIZE] [SIZE=2] $ 250.00 [/SIZE]
    [SIZE=2]Jet Lites Shadow Lithium[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]Knog 605[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Light and Motion Vega[/SIZE] [SIZE=2] $ 175.00 [/SIZE]
    [SIZE=2]Levin Brightstar[/SIZE] [SIZE=2] $ 270.00 [/SIZE]
    [SIZE=2]Light and Motion Stella 180L[/SIZE] [SIZE=2] $ 300.00 [/SIZE]
    [SIZE=2]Light On Expedition 1000[/SIZE] [SIZE=2] $ 800.00 [/SIZE]
    [SIZE=2]Lupine Betty 12[/SIZE] [SIZE=2] $ 1,185.00 [/SIZE]
    [SIZE=2]Niterider Minewt.X2[/SIZE] [SIZE=2] $ 190.00 [/SIZE]
    [SIZE=2]Niterider Trinewt[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]
    [/SIZE]
    impressive shootout...

    can't wait for the results

  19. #19
    mtbr member
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    Quote Originally Posted by francois
    [SIZE=2]
    [/SIZE]
    [SIZE=2]Light[/SIZE] [SIZE=2]Price[/SIZE]
    [SIZE=2]Ayup bar (regular kit)[/SIZE] [SIZE=2] $ 380.00 [/SIZE]
    [SIZE=2]Ayup helmet[/SIZE] [SIZE=2]
    [/SIZE]
    [SIZE=2]BR Lights Jeni H[/SIZE] [SIZE=2] $ 299.00 [/SIZE]
    [SIZE=2]BR Lights C2.1H[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Cateye Tripleshot[/SIZE] [SIZE=2] $ 330.00 [/SIZE]
    [SIZE=2]Dinotte 200L [/SIZE] [SIZE=2] $ 249.00 [/SIZE]
    [SIZE=2]Dinotte 200L Dual[/SIZE] [SIZE=2] $ 349.00 [/SIZE]
    [SIZE=2]Dinotte 600-LI-4C[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Exposure Enduro Maxx[/SIZE] [SIZE=2] $ 450.00 [/SIZE]
    [SIZE=2]Exposure Joystick Maxx[/SIZE] [SIZE=2] $ 250.00 [/SIZE]
    [SIZE=2]Jet Lites Shadow Lithium[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]Knog 605[/SIZE] [SIZE=2] $ 399.00 [/SIZE]
    [SIZE=2]Light and Motion Vega[/SIZE] [SIZE=2] $ 175.00 [/SIZE]
    [SIZE=2]Levin Brightstar[/SIZE] [SIZE=2] $ 270.00 [/SIZE]
    [SIZE=2]Light and Motion Stella 180L[/SIZE] [SIZE=2] $ 300.00 [/SIZE]
    [SIZE=2]Light On Expedition 1000[/SIZE] [SIZE=2] $ 800.00 [/SIZE]
    [SIZE=2]Lupine Betty 12[/SIZE] [SIZE=2] $ 1,185.00 [/SIZE]
    [SIZE=2]Niterider Minewt.X2[/SIZE] [SIZE=2] $ 190.00 [/SIZE]
    [SIZE=2]Niterider Trinewt[/SIZE] [SIZE=2] $ 500.00 [/SIZE]
    [SIZE=2]
    [/SIZE]
    Nice list.

  20. #20
    swag ho Administrator
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    Quote Originally Posted by James@GearReview
    Nice list.
    Hey James, talking to manufacturers, a couple of them mentioned you. They said you were awesome!

    fc
    IPA will save America

  21. #21
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    Quote Originally Posted by francois
    Hey James, talking to manufacturers, a couple of them mentioned you. They said you were awesome!

    fc
    Thanks!

  22. #22
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    That ought to keep you busy.

  23. #23
    conjoinicorned
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    ummm...lumen output is actually pretty easy to measure quite accurately.

    http://www.dasdistribution.com/produ...cal_models.htm

    light meters are cheap and measure in lux, which is lumens/square meter. measure output at the distance of interest. a decent quality meter is as accurate as the manufacturer specs for sure.
    what would rainbow unicorn do?

  24. #24
    swag ho Administrator
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    Another question: I understand a 10 watt HID is approximately 500 lumens.

    How many lumens is a 20 watt Halogen?

    fc
    IPA will save America

  25. #25
    conjoinicorned
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    Quote Originally Posted by francois
    Another question: I understand a 10 watt HID is approximately 500 lumens.

    How many lumens is a 20 watt Halogen?

    fc

    an "average" halogen should have around 16-20 lumens per watt.
    what would rainbow unicorn do?

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