squirtdad

Whats "better" 2 200 lumen lights or one 600 Lumen lights? I'm thinking of the LED flashlights that many are using. ie two cree 5 vs one PT7 if I have the terminology sort of correct?

thanks

hammond9705

I'm a big believer in always having 2 lights. If you ride in the dark long enough a light will fail. It's nice to have a second even if it isn't as bright as the primary.

J.C. Koto

+1

IMO, having multiple lights is generally better. Not only is there the (probable) safety in having a redundant system, multiple lights give greater flexibility in creating a suitable beam pattern. Sheer luminosity is nice and all, but lumens where they are needed is *far* more important. Think of this -- an ultra-bright hotspot 100 yards down the road is nice and all, but if there is little to no spill to the sides or foreground, think about all the hazards you're *not* seeing...

I'm a big fan of multiple, inexpensive lights. And far more battery power then I'll ever need in one ride.

Barabus

two 600 lumens lights are better!!

squirtdad

ok so you watched the debate last night......

J.C. Koto

Touche!

cyccommute 

A single source of light carries further and is usually better than 2 sources of light. Light passes through the atmosphere and absorbed and refracted as it does so. The amount the light is absorbed and scattered is related to the intensity of the beam. Think of it this way, if you took 1000 maglites and banded them together to make a light as intense as a search light would they light up the clouds the way a search light does? Probably not...and you'd need more than a thousand

Bottom line: Get the brightest single source you can.

Edit: +1 on redundant lights. No matter what you use, get 2. Stuff happens and it's a little appreciated fact that it gets dark at night.

kuan

Sometimes you only need 80 lumens. Get two lights.

cyccommute 

You may only need 80 lumens. I'm going to blast out 57 times that in just about any situation

znomit

Bar mounted? One 550lm light and one 50lm backup.
Otherwise yeah a 200 on bars and a 200 on helmet is probably similar to a 600 in terms of usefullness.
Cycco scattering is percentage based, not intensity(unless you have a million lumens and vaporise anything in its path) and happens almost entirely in the bulb/optics. For a bike light travelling 20-50m atmospheric attenuation is negligible unless in fog or rain.

wmodavis

Better is in the eye of the beholder.

john bono

I will initiate a 300 billion lumen lighting program. Every American must have a 300 billion lumen lamp. It's in the constitution or something.

cyccommute 

Scattering is probably too broad a term, however, I'm not talking about the scattering and light losses that occur only at the source. Light from 2 sources just does not have the same intensity at a target of some fixed distance from the source as light of equal output coming from a single source.

Bike light manufactures (and us cyclists) play this game all the time. I put out 4600 lumens but that's from 3 sources of approximately 1550 lumens each. In actuality, the light hitting the ground is something less than what a single 4600 lumen lamp would put out. Some companies put out lamps that have 3 emitters that put out 200 lumens each and then claim that the lamp is a 600 lumen lamp. It is but...

Consider, for example, a wave model. You have a stone of 600 g. You also have 3 stones of 200 g. A single person throws the 600g stone into a pond and measures the wavefront produced. You have 3 people throw the 3 stones of 200g at once and measure the wavefronts. The displacement is the same but the wavefront for the 3 stones will be lower than the single stone. Since each of the 3 stones is slightly different, follows a slightly different path and strikes the water at a slightly different time, the wavefront will never be equivalent to the single stone. The same happens with lights.

Consider a photonic model now. A single 600 lumen lamps puts out exactly the same number of photons as the three 300 lumen lamps. However, the 3 lamps' photons follow a different path from each other. Some light is reflected, some refracted, some absorbed along the path to the target. Where it occurs is unimportant. The single lamp's photons follow a single path and are subjected to the same attenuation along the way as the 3 lamps but because they are more 'coherent', more of them strike the target at the same time and thus has more apparent intensity. That's why a light with a higher output is 'brighter'.

Throwmeabone

I'm not quite convinced. To me it sounds like you're saying if you fill up a bucket of water from a single tap, the water is somehow different than if you filled it up from 3 separate taps.

hammond9705

I disagree that more is always better. At some point more light doesn't help, and just angers oncoming drivers and/or pedestrians and runs batteries down quickly (or needs a great big battery). I rode for a long time with a single Dinotte 200l. That is probably the bare minimum for me, but I can't see ever needing more than 600 or so. My eyes aren't that great, but unless you have no night vision I got to believe that for most people 4600 is a big overkill.

noamb

It's just not true that the amount of light from N conventional (non-laser) sources is smaller than the amount of light from 1 source, N times as bright. Coherence is only relevant for coherent light sources, i.e. lasers, and scattering at any physically reasonable intensity (i.e. not a huge tightly focused laser) is linear, so at a given distance and conditions (lens, fog, etc) some fraction will be absorbed/scattered.
90% of 200 is the same as 90% of 100 plus 90% of 100.

Besides, how do you know that your X lumen LED isn't just two X/2 lumen LEDs in the same package?

The emitting things (LEDs, filaments, whatever) put out some amount of light, and they illuminate some area at a given distance, and the intensity is just the power, i.e. energy per unit time, (that makes it past the lens) per unit area.

Now all of this isn't to say that in practice a single brighter light won't look brighter than two less bright ones (with the same total lumens, or whatever your measure of preference is). There are two reasons I can think of why this might happen:

1. It's hard to aim two smaller sources exactly parallel, so they tend to illuminate a larger area, and therefore have lower intensity (power/unit area).
2. If you look directly at the lights (from close range, where you can resolve the two), your eye is sensitive to intensity, and you see two spots each of lower intensity, so you get the impression of less brightness.

uke

I'd vote for two 600 lumen lights. Barring that, I'd pick one 600 lumen light over two 200 lumen lights.

varuscelli

Here's one way to get 600 lumens...but you need some pretty strong neck muscles to keep your head from slumping to one side.

Cadd

What kind of light do you guys have that produces 600 lumen?

uke

Any decent P7 will produce at least 500 lumens.

Cadd

I'm sorry....I'm not familar with "P7". And I can't seem to do a search with just 2 letters =(

wrobertdavis

I bought two 400L lights from Dinotte. After trying them (one on handlebars and one on helmet), I was feeling like I wanted a little something more. I wrote Dinotte and asked about their 600L. They kind of discouraged it as being not much more value (about 30% more light than a 400L). The 400L was their latest technology light at the time. They encouraged me to play with the different lenses. I found that that real secret was mounting the headlight at an angle that allowed me to use the light without any concious strain on my neck. I also changed one of the bar mounted lenses to a medium instead of the spot lens. The two lights complement each other to create a broad distinct pattern that is quite impressive.

I am definitely sold on the idea of a helmet mounted light. It allows me to see around curves and to spot game (rabbits, armadillos) a long way off.

Bob

GTALuigi

there are at least 2 strong topics about the P7 in this very same section of the forum, check them out.
is currently floating high on the forum waves.

mechBgon

Beam patterns and runtime are a couple more factors to keep in mind.

If the rider wants to see far down the road, then even one well-chosen Cree Q5 light would be better than a P7. Point in case: which is better? DiNotte 600L (~600 lumens in a floody beam) or Dereelight DBS V2 (~260 lumens in a focused beam)? If you want to see down a road or highway, then the DBS is much better, even with less than half the lumens. The excellent throw of the DBS makes it far easier to avoid obstacles at speed.

Corrolary to that, runtime is also important. When considering a light setup, think through your typical usage pattern, when you'd recharge batteries, and whether you'd be OK with carrying spare batteries to swap into a flashlight mid-ride or not. Try to find real-world runtime numbers for the lights you're thinking about.

I lent out my DiNotte 600L to a co-worker, and for road riding, I really don't miss it, 600 lumens or not. The DBS and my helmet-mounted Olight M20 R2 are better suited to road riding, since they have much better throw. I might occasionally need more runtime than the DBS will do on one battery (1.7 hours), but that's why I've got a Seca 700 Ultra on order

cyccommute 

I'll agree that running 3 lamps as powerful as mine is a bit over the top. I do it because I can. However, I've used less light starting with modified flashlights, a short period with bottle generators, battery powered Cat Eyes (about 60 lumens), overvolted Niteriders (~200 lm), nominally volted Niteriders (~100 lm), multiple overvolted Niteriders (~1200 lm), LED (~100 lm) and my current set up. I much prefer more light than less. The lights I currently use put out much more light the the Niterider with the same battery packs. The heads are a little larger but not significantly heavier than the other ones.

I have no night vision problems and can navigate quite will in the dark at walking speed. But if I want to go more than walking speed, I want some light to see by. Once you flick on a light, no matter how small or weak, your night vision is shot. You are night blind. It a function of the rod cells in your eyes and their sensitivity. Just about any light source can oversaturate them and you are stumbling around in the dark. A weak light only over saturates them and leaves you night blind without enough light for the cones cells to take over.