LX -101 Light meter question-

[Silviron]

Pardon me if this is a stupid question, or if my reasoning is totally out to lunch...

Ok, I understand that we are supposed to measure our lights from one meter on these things (Thanks Craig, for that answer from a couple months ago), since one LUX is equal to one lumen per square meter, one meter from the source...

So, if we put our light source directly on the sensor, would the reading be (at least a rough approximation of) the total light output in LUMENS?

 

[PeLu]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Silviron:
since one LUX is equal to one lumen per square meter, one meter from the source...
<HR></BLOCKQUOTE>

Look at Lumen like the 'amount' of visible light (not regarding time here). If you distribute one Lumen over one square meter, you will have one Lux. Independent how far you are away from your source.


<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>So, if we put our light source directly on the sensor, would the reading be (at least a rough approximation of) the total light output in LUMENS?<HR></BLOCKQUOTE>

No, this does not work at all. An easy, but dissatisfying explanation:
measuring luminous flux (in Lumen) requires an integrating sphere and some other expensive equipment. Do you think then it could be that easy?

Usually it is said that you have to be at least 5 times the light sorce's largest dimension anway.
Only if you have a light source where you know it radiates equally in all directions, or you have the exact light distribution diagram, you may get your lm out of one lx measurement.