Recommendations for a light meter

I am thinking about purchasing a light meter and I would like some ideas. I am still struggling with understanding the different units. Foot candles, lux, candela. I have not found any conversion between the different units. I also want to be able to check lumen output and I was talking to a physicist that I work with and he felt it would be fairly simple to build an integrating sphere. My understanding is that it is a white on the inside ball with a light meter on the side. I have no idea how a person would calibrate it. Sometimes it is really helpful not knowing how difficult something is. What do you think? Is it possible or should I just go outside in the dark and play with my lights.

Thanks,
Alex

Here's a thread on the latest one to pop up. I wouldn't call it a steal, but i'm not sorry i bought it. I get the impression that you're interested in a better one, though.

http://www.candlepowerforums.com/ubbthreads/showflat.php?Cat=&Number=1041082&page=&view=&sb=5&o=&fpart=1&vc=1

Hello Alex,

Although it may be fairly simple to build an integrating sphere, there must be a little more to it. Otherwise they would not get the $10,000-$15,000 they are asking for them.

Light meters run a wide variety. The Wavetek Meterman LM631 seems to be quite popular around here. I have the Extech EA30 and am quite pleased with it.

Tom

Thanks very much for the recommendations. I've been trying to understand what it takes to put together an integrating sphere. My understanding is that the sphere is an attempt to take all the variation in the brightness of a light source and average it out so that a reading of the light intensity will correspond to the total lumen output. I imagine that what the surface is painted or coated with is important, must be a very reflective white. I also think that placing the meter in a location that receives only reflected light would also be important. What I don't have clue about is how to calibrate this homemade sphere. Maybe it is just a case finding a testing lab and charting out a series of known light sources. I really like the idea of ordinary people being able to test out the claims of manufacturers and distributors. I'm very happy to see the run time tests and lux readings that are posted on CPF, I believe helps toward keeping the claims accurate.

Thanks,
Alex

[ QUOTE ]
peskyphotons said:
I am thinking about purchasing a light meter and I would like some ideas. Thanks,
Alex

[/ QUOTE ]

Hi Alex, I have the Extech 401036 http://www.extechproducts.com/
This meter is a few more bucks but has some really nice features. It logs and comes with graphing software. If you are interested in runtimes the logging feature is pretty handy.