How do I use my light meter?

I don't know where else to ask. I have a fisher scientific 06-662-63 light meter. here is the page on it: https://www1.fishersci.com/wps/port...ut=true&brCategoryId=56441&hlpi=y&fromSearch=
I've never used one before.
I need to measure the light in a room for a research project. I need to have the room very dim (.10 lux) the meter apparently doesn't go that low I have a couple of pictures of the device here: http://picasaweb.google.com/seth.hollen/LightMeter in the picture it says "620" does that mean 620 lux (this was in a well lit room with fluorescent bulbs)

I was hoping it would mean 6.20 lux as apparently I need accuracy to 2 decimal places. I'm not even sure if this is the right forum to post this in. any help is gratefully appreciated.

Hello Seth,

It appears that the resolution of your meter is 1 lux. I believe your reading shown in the picture is 620 lux. In order to read 0.1 lux, you will have to use the output terminals and a volt meter. Set your volt meter to 200 mV and 0.1 lux will be 0.01 mV.

If the distance between your light source and your object is adjustable, you can use the inverse square law to calculate how far to move it back to obtain the level of light you want.

For example: Let's say that you are reading 620 lux at 1 meter and that the distance between the light source and your object is adjustable.

620 lux at 1 meter will be reduced to 1 lux at 24.9 meters. To get down to 0.1 lux, you will have to back up to 78.74 meters. As you can see, this is probably not practical, so let's look at starting with an illumination of 1 lux at 1 meter. At this level, you only have to back away 3.16 meters to get the level of light down to 0.1 lux.

Tom

Thanks for the info. I was afraid it only showed 1 lux. I'm not sure why this was supplied to us as we are supposed to verify .10 lux.
Oh well.

I was hoping at first I could somehow use it to test my flashlights lumens
When I shine my modded Q3 at it all the reading go off the chart though

How critical does this measurement NEED to be? What are the acceptable limits?

The link indicates "With certificate verifying traceability to NIST." That's fine that it is calibrated, however the accuracy of your measurement may invariably be far worse than you may ultimately be willing to accept since the measurand (phenomena to be measured) falls in the lower range of the measuring device.

setherd said:

I don't know where else to ask. I have a fisher scientific 06-662-63 light meter. here is the page on it: https://www1.fishersci.com/wps/port...ut=true&brCategoryId=56441&hlpi=y&fromSearch=
I've never used one before.
I need to measure the light in a room for a research project. I need to have the room very dim (.10 lux) the meter apparently doesn't go that low I have a couple of pictures of the device here: http://picasaweb.google.com/seth.hollen/LightMeter in the picture it says "620" does that mean 620 lux (this was in a well lit room with fluorescent bulbs)

I was hoping it would mean 6.20 lux as apparently I need accuracy to 2 decimal places. I'm not even sure if this is the right forum to post this in. any help is gratefully appreciated.

Click to expand...

0dBm said:

How critical does this measurement NEED to be? What are the acceptable limits?

The link indicates "With certificate verifying traceability to NIST." That's fine that it is calibrated, however the accuracy of your measurement may invariably be far worse than you may ultimately be willing to accept since the measurand (phenomena to be measured) falls in the lowest settings of the measuring device.

Click to expand...

I don't know. Personally I think it's BS. this is a research study and they come up with all these great sounding criteria but then they want a non-technical person to use the equipment. I'm not supposed to be doing the measurements, but I'm the most qualified.

I'm just making the room as dim as I can with out being completely dark.