Light micro-fluctuations in brightness or defective luxmeter?

[csshih]

Hi All,
I recently purchased a datalogging luxmeter: the Extech HD450, but I have some questions regarding measuring lux.

As a benchmark, I've been comparing my readings to Selfbuilts, as he has quite a bit more experience than me... but, I've run into many discrepancies and what appear to be anomalys (to me)

As I tried to find out why, I realized that peak readings were dramatically different from normal readings. (Which,now, I can see is reasonable.)

Here's a bit more info to explain the problem better:
The meter has quite a few functions, one of them is Peak Lux.
That feature captures 10µs peaks.. that is, 1/100,000 of a second, undetectable by the human eye.

Now, my question is:
How much do lights fluctuate?

Here are a few of my readings, PEAK is in RED.

ThruNite Catapult: 24,860 lux 34,450 lux
Eagletac M2XC4: 25,110 lux 35,610 lux
Solarforce l950m: 12,590 lux 17,130 lux
Tiablo ACE-G: 11,630 lux 16,640 lux
Epsilon ED-P72: 15,560 lux 21,250 lux
Solarforce Masterpiece: 15,790 lux 22,050 lux
~40% increase (+/- 5%)

My room, lit by CFLs 13.2 18.5 lux
DO'H. stupid me. I should have remembered what my physics teacher taught me about math.

 

[sparkysko]

Wouldn't surprise me if the drivers inductors are causing those bumps. Find out if it happens on something that's direct drive or just uses a resistor.

 

[csshih]

alright.. more to add to my confusion...
it happens with an incandescent light, too..

Surefire P60 2580 lux 3708 lux

perhaps it is a defective luxmeter?
all the readings seem to be consistently bumped up 40%

DO'H. stupid me. I should have remembered what my physics teacher taught me about math.