Got my light meter Yeah! Have questions Boo!

[mattchase]

I just got my new light meter that is an imported Chinese unit, so the instructions are a bit lacking. There are two particular things I'm wondering about, first is I have been comparing my L0D CE and MiniMag LED readings to those on Flashlightreviews.com, and when using the default settings (turn the power on, take readings) and direct readings (throw), I get numbers that are from 20%-35% lower. The same is true in doing the milk carton tests, the readings are a fair amount lower. However, when I go to PEAK mode all my numbers come up very close to what are on Flashlightreviews.com (within 2-5%). So is it as simple as this is the mode I need to use? Why is it that this mode gives such higher readings compared to the default mode?

Here is what is in the manual regarding Peak mode:

"Peak-hold function for tracing the peak signal of light pulse with least duration 10(microseconds) and keep it."

"Peak-hold recorder mode: Press and hold down PEAK key until display shown the "CAL" letter, then press PEAK key cycle through Pmax and Pmin recorder mode, and expose the photo detector to light pulse measuring field. Press the PEAK key again to exit PEAK recorder mode, then the meter will resume normal operation.

Holding the PEAK button down for a period of time doesn't do anything, it basically pauses / freezes the unit up until you let go of the button, and once done this doesn't bring up "CAL". I think this is a case of lost in translation though as MANU appears on the LCD, which I'm assuming is short for manual but am not sure.

Secondly there is a Relative reading mode, which the manual says:

"Press REL key to enter Relative mode. The display shown zero value and the current reading will be stored as a zero-in value. Press again to exit this mode"

My understanding was that this mode allows me to zero out the meter when using it under ambient light levels, which it actually does do. The problem I'm having is that upon shining a light on it it immediately goes to OL, unless the light is under about 250 lux. The meter automatically adjusts itself for the various ranges, so I'm thinking perhaps it isn't adjusting itself to the next highest range correctlyin Relative mode? The problem with that is there is no way to change it manually (that I can see). I'm going to email the place I bought it about this second issue as well, just hoping some one here might know something too.

Thanks!

[Bullzeyebill]

Not sure about your meter, but I stay away from the peak, and peak hold modes using my Meterman LM631. It is diffficult to compare readings of one lightmeter to the other, even within the same model. See electronic, battery, etc forum and find sticky "thread of interest", and go to Light Meter Benchmark Testing - CPF style.

The best purpose for a personal lightmeter is testing and comparing your lights to each other. Also good for posting your results, understanding that they are your results, and someone else's meter reading results may differ from yours.

I have learned a lot about my lights, and when I read that someone has tested a light in a Integrated Sphere and I have that same light I can then make some judgments about what the output of my light might be and use that info to "calibrate my lightmeter" , knowing that there might be a + or - factor in accuracy based on variables in led output between different lights, etc. During the passaround Benchmark Testing period I was able to compare my "bounce output readings" with the passaround lights that had been tested in an IS.

Use of my lightmeter is fun, and provides good info for me, and to me is better than subjective guessing about light output and lux.

Bill

[mattchase]

Thanks Bill. I'm going to go read through the benchmark testing thread.