festivus said:
I hate to disagree but I think you're getting mixed up between lumens and lux (which does relate to beam and isn't directly comparable - not really used anymore).
Lumens is a measurement and can be compared - it doesn't give any indication to beam distance etc. But if you go into a dark room with white walls and shine a light with 1000 lumens it will fill room with a certain amount of light pretty much regardless of throw (tightness of beam).
A 2000 lumen light will light the room more. It may not seem twice as much because of the way your eyes see light.
festivus said:
I hate to disagree but I think you're getting mixed up between lumens and lux (which does relate to beam and isn't directly comparable - not really used anymore).
Lumens is a measurement and can be compared - it doesn't give any indication to beam distance etc. But if you go into a dark room with white walls and shine a light with 1000 lumens it will fill room with a certain amount of light pretty much regardless of throw (tightness of beam).
A 2000 lumen light will light the room more. It may not seem twice as much because of the way your eyes see light.
I don't believe I'm confused. Lumens measures the amount of light coming from a source (LED in this case). Lux is the number of lumens per square meter.
Unless you disperse those lumens over an area, higher lumens doesn't mean a room becomes better lit necessarily, just that there are more lumens of light in the room. A laser and a light bulb both emit light, the laser is so focused you wouldn't use it to light a room, nor would shooting it into the ceiling necessarily light the room better than a light bulb. The bulb lights the room, but it can't cut steel at the same lumen level.
Or to steal from a website:
The relationship between lumens & lux
One Lux is defined as being equivalent to one lumen spread over an area of one square metre, or to put it another way – a measurement of lux (light intensity) tells you how many lumens (total light output) you need given the area you are trying to illuminate.
So 1000 lumens, concentrated into an area of one square metre, lights up that square metre with a light intensity (illuminance) of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux.
Therefore, lighting a larger area to the same measurement of lux requires a larger number of lumens – which is usually achieved by increasing the number of light fixtures (and the power consumed).
The problem is in real life you have to consider the area you want to illuminate. Lighting a room and lighting a pinhead can be done with the same number of lumens, it just depends how bright you want it to be. That's where lux comes in. Technically you can *light* a room with 100 lumens and pinhead with 100 lumens, it'll be really easy to see that pinhead, kind of dark in that room though.
A problem with using lux is you'd have to standardize the area you measure all the lights against. As using the pinhead example everyone would make a light that basically shoots a laser beam to up their lux values. Festool would then still be making a light to illuminate a room and would show lower lumen & lux values.
So I should've really said you can't use only lumens, it is part of the picture, but I don't know that it is too meaningful in a lot of situations. Now if I want efficiency (lumens/watt) then that's great. If I want to know they're cranking out a lot of light from a unit, sure, but I still need to know the area/lux so I can determine which will work in my specific scenario.
And a Sys-well? [tongue]
