The Planted Tank Forum - View Single Post - Spectral Analysis for LEDs for use over planted aquaria; Graphs here!
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post #12 of (permalink) Old 05-09-2011, 01:03 AM
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Originally Posted by plantbrain View Post
A PAR meter is a quick easy thing and someone will get it some time at some point, that I am less worried about.

It can depend on the lens, the spread, driver and area etc more so than say T5 lights.........

You can predict the PAR somewhat based on the graph, but not that much really. You need the lens type, area, distance and pattern of lamps, this can vary all over the place.
Tom, I don't believe anyone can predict the PAR at all based on those graphs. There is no absolute value assigned to the vertical axis, and, without that, the graphs are just more illustrations of what the manufacturers provide in their specs for each LED. I would infinitely rather see PAR numbers at various distances, both from the LED on center, and at distances from the center, and at 3 different LED currents. With those numbers it is easy to predict the PAR for any current, any number and spacing of the LEDs.

Unfortunately it also requires a set of those numbers for each optic that would be used, a 60 degree and a 40 degree at minimum. I'm really looking forward to seeing that type of data.

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