Hi-spec lights, il-lumen-ate me please

[Chuffy]

Ok, this might seem like a daft question, but...

There are some high end lights out there, kicking out around 1000 lumens. These lights have multiple LEDs, each putting out about 200 lumens.
So, if all you are doing is adding extra LEDs, do you just get a brighter beam, but no extra distance or width?
The best analogy I can think of is with sausages. One stuffed with 100g of meat, the other stuffed with 400g, but each sausage being the same size. Substitute lumens for meat and you'll get it.

What I'm really after is, does the lumen figure actually give you a clear idea of how good the light is, or is it one of those false performance figures, like the 0-60 time of a car?

My physics is pretty ropey, so be gentle with me...

 

[Fiona N]

My understanding is that light declines as the square of the distance or, more simply, double the distance, one quarter the light. E.g. 100 lumens reaching 10metres, 25 lumens at 20m and a dim 6 lumens at 30m. So adding more LEDs to increase the lumens at the source should increase the amount of light reaching some distance ahead of you. To continue with the arithmetic - if you quadruple the light at source, then the light at 10m will be about 4 times greater too but will still decline quickly - although you'll get 6 lumens at 40m giving you better vision further ahead as well as more light at shorter distances.

Hope this helps.

 

[yenrod]

>il-lumen-ate me please

I'm a bit 'thick' on thee owld lights !

 

[Chuffy]

One of these two responses is quite helpful....

Thanks Fiona!

 

[andrew_s]

There's a certain amount of confusion in the units. Lumens is the power of light that comes out. It could be used in a narrow pencil beam to produce a small brightly lit spot, or it could be spread really widely and seem much dimmer.
The measurement of how brightly the ground is lit is the "Lux". It is measured at a point, and says nothing about how big an area is lit. It's usually German manufacturers who quote lux figures, which are normally measured at 10m. This is because german road regs specify how bright bike lights should be in lux at 10m. If you get non-German companies quoting lux (or candlepower), they also have a tendency to produce lights with very narrow beams so they can quote a big number on the packet.

If you double the lumens, keeping everything else the same (eg use 2 similar lights), then you get double the lux (brightness) everywhere.
However, since your eyes adapt to the amount of light, having double the light far off doesn't do as much good as it would if there wasn't the even more brightly lit area close to.
In an ideal world, a multiple LED light would have one or two flood LEDs to provide good close to lighting, and have the extra LEDs on narrow spot beams to light up areas further off without putting so much light in the near field that your eyes adapt. I suspect that not many bike light makers do this.

 

[HJ]

It is not just about the light source, it is also what you do with it. The reflector and lenses are also important as this effect how much of the light is used. Which is why I rely on reviews such as this one (yes it is the same one I always roll out), hopefully there will be one for this years crop of lights soon...

 

[Chuffy]

I guess the only true test is how the light performs in the Real World (tm). For the purpose of a review, beamshots are pretty essential, yes?

 

[Fiona N]

In an ideal world, a multiple LED light would have one or two flood LEDs to provide good close to lighting, and have the extra LEDs on narrow spot beams to light up areas further off without putting so much light in the near field that your eyes adapt. I suspect that not many bike light makers do this.

That's a good point and is well illustrated (illuminated ) by my own lighting system - I use a pair of Lumicycle lights and normally ride on the narrow beam which is only 7w (I think). If I need to make myself more noticable to oncoming traffic, I switch on a much larger flood which nicely illuminates the immediate area but diminishes how far ahead I can see.

Thanks for the Lumens/Lux explanation too.

 

[mr Mag00]

yh for another lumicycle user

 

[mr Mag00]

I have just found out tonight that you can replace the mr11 in a lumicycle halogen set up with an led equivalent, has anyone done this yet and do they have a good supplier?

 

[Chuffy]

I have just found out tonight that you can replace the mr11 in a lumicycle halogen set up with an led equivalent, has anyone done this yet and do they have a good supplier?

Any more info Mr M?

 

[mr Mag00]

well i saw this on the lumicycle website.
they are selling the 1 watt 15 led equivalent for £20!!! so i looked online and you can get them for around half that, i spoke to a electrical wholesaler today, who funnily enough had another enquiry yesterday!! he says he should be able to match any online price and I asked if he could find them with both flood and narrow beam as these are avialable from lumicycle.

according to the lumicycle site as these use around 1watt you should be able to run for hours i mean atleast 40hours from one of their ordinary batteries. so i am looking at buying a lamp for my helmet too.

 

[Chuffy]

well i saw this on the lumicycle website.
they are selling the 1 watt 15 led equivalent for £20!!! so i looked online and you can get them for around half that, i spoke to a electrical wholesaler today, who funnily enough had another enquiry yesterday!! he says he should be able to match any online price and I asked if he could find them with both flood and narrow beam as these are avialable from lumicycle.

according to the lumicycle site as these use around 1watt you should be able to run for hours i mean atleast 40hours from one of their ordinary batteries. so i am looking at buying a lamp for my helmet too.

Ah. I have the 15 LED 1w lamp. If you have a glow ring and only ride/commute on lit roads and only need a light to be seen by, then it's great. Silly run times and very visible. Sadly, if you want a light to actually see by then you would be better off training a small marmoset to sit on your bars repeatedly lighting matches.

It is not to be confused with their new LED lamp.

 

[mr Mag00]

oh, so not used for navigation then? i am on unlit roads. i havent seen thier new led system, it was on their site i saw the replacement led lamps

 

[Chuffy]

oh, so not used for navigation then? i am on unlit roads. i havent seen thier new led system, it was on their site i saw the replacement led lamps

Just to be absolutely sure. We are talking about this

aren't we?

If so, sorry but it's rubbish as a light to actually see by.