Interesting for those of us who use the clubs par meter to measure our lights.

chirocato · #1 10/17/2007, 10:04 PM

Been reading in the lighting forum and came across this from ATI.

"The spectral response of the Apogee Sensor used in Quantum Meters and the Quantum Sensor is shown at right. As the figure indicates, the sensor underestimates the 400 to 500 nm wavelengths (blue light), overestimates the 550-650 wavelengths (yellow and orange light), and has little sensitivity above 650 nm (red light). Fortunately, common light sources are mixtures of colors and the spectral errors offset each other. The sensor measures green light (500-550 nm) accurately, so it can be used to measure the radiation inside and at the bottom of plant canopies."

Sheds some light on what we think we are measuring isn't actually accurate.

CulturedAquatic · #2 10/18/2007, 07:45 PM

I just listen to a pitch about light reading and Quantium meters at the last MACNA. I haven't read the light forum, but I did just buy a Quantium Meter. Based on the presentation, it is a very good investment. I'll have to get my notes out and compare them to the forum you referenced.

chirocato · #3 10/18/2007, 08:16 PM

Quote:

Originally posted by CulturedAquatic
I just listen to a pitch about light reading and Quantium meters at the last MACNA. I haven't read the light forum, but I did just buy a Quantium Meter. Based on the presentation, it is a very good investment. I'll have to get my notes out and compare them to the forum you referenced.

I'm with you. I was at that same lecture at MACNA. I am borrowing my clubs Apogee Quantum meter to take readings now. It got me to thinking though.

InsaneClownFish · #4 10/19/2007, 12:25 PM

Although I wasn't at MACNA, so I can't comment from first hand experience, this seems an awful lot like a pitch for their own product.

While I don't doubt some of the validity of what they are trying to illuminate(pun intended

) I don't think it invalidates the use of PAR meters as tool of comparison.

CulturedAquatic · #5 10/19/2007, 12:52 PM

The pitch at MACNA was by one of the renowed speakers (Dana Riddle). I was under the impression the pitch was an independent study by Dana. Here are some old articles about his previous lectures. Maybe someone can dig up some more resent ones.

http://www.athiel.com/aquatic/riddle3.htm

http://www.athiel.com/lib4/par1.htm

Obi-dad · #6 10/19/2007, 03:31 PM

True that it underrepresents blue - but it is much much more accurate than typical 'lux' or camera light meters which are heavily weighted to yellow/green to approximate the human eye response.

The PAR meter may not give you absolute measurements, but it is still good for determining when your bulbs need to be changed, relative strength between different bulbs, etc.

InsaneClownFish · #7 10/19/2007, 04:01 PM

Quote:

True that it underrepresents blue - but it is much much more accurate than typical 'lux' or camera light meters which are heavily weighted to yellow/green to approximate the human eye response.

The PAR meter may not give you absolute measurements, but it is still good for determining when your bulbs need to be changed, relative strength between different bulbs, etc.

Well said.