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The Lumix/Candles/Watts conundrum

pinnopinno Posts: 39,165
edited October 2012 in The bottom bracket
Yes I know this should be in Workshop or something - I don't care :P

Can someone explain the relative brightness of the different measurements of output. Is there a conversion table ?
My 2 Smart lunars are one and a half and two and a half watts (respectively) output and they're pretty good.

PS I am planning a raid on Aggies basement.
S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
W - (still at Atlantic boulevard). Neill broke his collarbone.

"Why are the tractors beeping in the night? I dunno woss goin' on"
Tricky, 9yo

Posts

  • team47bteam47b Posts: 6,424
    P(W) = ΦV(lm) / η(lm/W)
    my isetta is a 300cc bike
  • team47bteam47b Posts: 6,424
    oh I forgot you'll need this bit too :D

    The power P in watts (W) is equal to the luminous flux ΦV in lumens (lm), divided by the luminous efficacy η in lumens per watt (lm/W)
    my isetta is a 300cc bike
  • pinnopinno Posts: 39,165
    Just had a look at this:

    The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all light emitted, independent of the eye's ability to perceive it.

    Okay Team47b smarty Portugese pants, here is a question for you - why don't manufacturers stick to a standard method of measurement ? After all, as a consumer we need to have a yard stick or should I say Lumen Beam, to help make the comparison between one set of lights to another. So your equation is not going to help me decide.
    Is there a direct comparison between Lux and watts ?
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • team47bteam47b Posts: 6,424
    Sorry, I was havin a larf.

    You can only compare the brightness of the various light sources on the market by knowing the number of lumens they produce to use as a standard measuring device. You can make a comparison by finding out the lumens per watt, standard light bulbs are about 12 lumens per watt, LED about 40 lpw, strip lights about 60 lpw.

    They should of course just tell us how bright it is compared to a 60w bulb cos we all know how bright that is, lumens are based on candle power but I think a candle would just blow out on a bike in the weather you're having!
    my isetta is a 300cc bike
  • pinnopinno Posts: 39,165
    team47b wrote:
    Sorry, I was havin a larf.

    ...LED about 40 lpw...

    Are you sure ? I built a 1/32 scale racing circuit for my neices. The LED's I used were between 10,000 and 17,000 millicandles. In fact, the range of LED's is huge.

    8102526194_3b28d11452_m.jpg

    8102515727_0a816b572c_m.jpg

    8102543392_acbc5dc23f_m.jpg

    8102546170_29794a0074_m.jpg
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • team47b wrote:
    P(W) = ΦV(lm) / η(lm/W)

    If you do that backwards you create dark. :D

    Its actually the formula for Stoke.
    The dissenter is every human being at those moments of his life when he resigns
    momentarily from the herd and thinks for himself.
  • pinnopinno Posts: 39,165
    team47b wrote:
    P(W) = ΦV(lm) / η(lm/W)

    If you do that backwards you create dark. :D

    Its actually the formula for Stoke.

    The Dark is the place where you do most of your misdameanors with CB and Stoke is probably the best place to do it 'cos no one would bat an eyelid there. So don't knock it. (Dodgy doings of a sexual nature by cyclists is called 'clunging', for those not in the know.)
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • team47bteam47b Posts: 6,424
    You are right, I went to Stoke, twice, it was dark both times, I will recalculate the formula.
    my isetta is a 300cc bike
  • pinnopinno Posts: 39,165
    I have been to Manchester a few times unfortunately. It was always raining. Whats the formula for rain in Manchester ?
    Thankfully I haven't been to Manchester in the dark so I cannot compare it with Stoke.

    Still raining here...oops, Warning thread crossover thread crossover.
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • GizmodoGizmodo Posts: 1,928
    The formula for rain in Manchester is 2rA^n (where rA is the rain fall in Anglesey and n is the number of bikes you own).

    The best way of improving your bike light efficiency is to move South to somewhere like Portugal like Team47b, Scotland is so far North that you won't see the sun again now until April (if you're lucky).

    Edit: it's still better than Stoke where you can see the Sun but only if you buy it from a newsagent.
  • pinnopinno Posts: 39,165
    For Cleat and Claire Balding

    On this thread; wondering if I can save on batteries by moving to Portugal. Don't think i could put up with the constant adulation of that greasy spick Ronaldo.

    Whats the formula to decide whether its worth moving or not ?
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • team47bteam47b Posts: 6,424
    Sr Ron lives in Spain.

    Formula:

    Give up work @50 + 350 Days pa sunshine = Smug barsteward :D
    my isetta is a 300cc bike
  • carrockcarrock Posts: 1,275
    Just had a look at this:

    The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all light emitted, independent of the eye's ability to perceive it.

    Okay Team47b smarty Portugese pants, here is a question for you - why don't manufacturers stick to a standard method of measurement ? After all, as a consumer we need to have a yard stick or should I say Lumen Beam, to help make the comparison between one set of lights to another. So your equation is not going to help me decide.
    Is there a direct comparison between Lux and watts ?

    To be fair the decent manufacturers do all list output in lumens. The ones who advertise candelas or whatever do so to hide the fact that their rubbish light puts out about 50 lumens. As a rule of thumb, buy something that puts out at least 400 lumens and it will be bright enough
  • pinnopinno Posts: 39,165
    carrock wrote:
    To be fair the decent manufacturers do all list output in lumens. The ones who advertise candelas or whatever do so to hide the fact that their rubbish light puts out about 50 lumens. As a rule of thumb, buy something that puts out at least 400 lumens and it will be bright enough

    Listen Carrock mate, that sensible logical stuff really wasn't in the spirit of things. Now I am going to have to warn you. This is your first cautionable offence and I am punishing you with this:

    Take that and don't do it again
    S - https://i.pinimg.com/564x/35/cd/f1/35cdf125f02216d233fc9aa90f8607e6.jpg
    W - (still at Atlantic boulevard). Neill broke his collarbone.

    "Why are the tractors beeping in the night? I dunno woss goin' on"
    Tricky, 9yo
  • Anyone for the inverse square law of illumination?
  • Anyone for the inverse square law of illumination?

    That would be R+R+aR +Ar+ R+r+ar+r = this
    The dissenter is every human being at those moments of his life when he resigns
    momentarily from the herd and thinks for himself.
  • carrockcarrock Posts: 1,275
    carrock wrote:
    To be fair the decent manufacturers do all list output in lumens. The ones who advertise candelas or whatever do so to hide the fact that their rubbish light puts out about 50 lumens. As a rule of thumb, buy something that puts out at least 400 lumens and it will be bright enough

    Listen Carrock mate, that sensible logical stuff really wasn't in the spirit of things. Now I am going to have to warn you. This is your first cautionable offence and I am punishing you with this:

    Take that and don't do it again

    Ah yes thought I was in Workshop for a minute there....
  • team47bteam47b Posts: 6,424
    the answer is 4100 lumens!

    http://www.wickedlasers.com/torch

    fit this puppy to your bike, set fire to communters/peds/cars etc
    my isetta is a 300cc bike
  • Nick FittNick Fitt Posts: 381
    Does the density of darkness enter into this anywhere?
  • Also, if nobody has actually weighed it - why is called light? :D
    The dissenter is every human being at those moments of his life when he resigns
    momentarily from the herd and thinks for himself.
  • On a serious note , a couple of years ago I watched a series of progs. on light, it started with the musings of various bods hundreds of years ago with associated very simple maths. As the series went on the musings & maths got longer & more intense, till in the end the blackboard ( it must have been 4 metres long ) was covered in calcs. & they admitted they still don't truly know.
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