I bought one of these because I needed a meter that would read down to very low light levels in our camera test lab. There are cheaper products available (we have a couple), but for a critical measurement, I trusted the B&K Precision name. As far as I can tell, the meter is accurate, and will indeed read down to very low light levels, but it's *very* slow when the light is dim. (I'm talking about levels less than 1 lux.) The spec for the meter says it updates 2x/second, and that's true as far as it goes: The digital reading updates twice a second. What's not mentioned is that there must be a huge capacitor across the sensor to reduce noise in dim lighting, so the value that's being measured by the digital part changes **very** slowly when the light level is low. At the lowest light levels we're measuring (~0.16 lux or so), it can take a good 15 seconds for the reading to stabilize.

This won't be an issue if you can afford to wait to make a reading after a lighting change (and obviously if your light source is quite constant), but if you need a faster response in very dim conditions, this probably isn't the meter for you. (It's pretty fast at higher light levels, I think it's just that in very dim lighting, the current through the photodiode is very small, so it takes a long time to charge or discharge the filter capacitor.)

(FWIW, I suspect this would be the case with other cheap light meters - or else if they have a much smaller filter capacitor, you'll get a lot of noise on the readings.)