Using a real light meter

[ALToronto]

I have given up on smartphone apps and bought a real light meter on Amazon. It's the kind with a separate sensor. Here's the link:

http://www.amazon.ca/gp/product/B00N0EBS3G?psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00

My problem: the instructions are entirely in Chinese, and my Chinese-fluent friends haven't been able to really help me figure it out because they know nothing about light measurement. So, going blind with this device, how do I calibrate and use it? Are all such meters, with separate sensors, basically the same?

 

[polyantha]

There is a pdf manual of the product 1010a. I think these products could be more or less the same. http://cdn1.globalmediapro.com/att/a/2/h/3/a2h3g1/1010amanual.pdf

 

[ALToronto]

Thank you, that is very helpful.

 

[naoki]

I'm pretty sure you can't calibrate it by yourself. There is a calibration service in Hollywood for expensive meters (Gossen, Sekonics etc), but it costs you around $78-110. George Milton of Quality Light Metric Co. is the good person for this service (maybe the only person in the US beside the manufacturer). Most sensors do shift with age BTW. For hobby growing, I don't think you need to worry about calibration too much. Approximate level is good enough, right? Also, you are measuring lux/fc (human eye perception) any way, and not plant-relevant PPFD.

No, not all meters are same. Different meters have quite different spectral response (almost all cheap meters deviate from the CIE luminosity function). So the comparison of measurements are somewhat problematic for artificial light. The x-axis of the sensitivity curve in the manual (polyntha's link) seems to be wacked; the peak is around 1200nm instead of around 550nm. It's probably a typo, though.