60 degree optics much nicer than 40

[zygote2k]

I just got 6 more of the PAR 38's today and 2 of them were 60 degree optics. I replaced a 40 degree and was surprised to see the amount of area that a 60 illuminates over a 40. No spotlighting with these. The PAR rating will drop with wider optics, but since the SPS are near the top, I don't think I'll notice any ill effects with a slight reduction of PAR.

[Coral Hind]

Can you post some PAR readings that compare the two?

[gmubeach]

I have 4 of the 60's and they are great!

[zygote2k]

Can you post some PAR readings that compare the two?

check them out at nanotuners- they have posted the par differences between 40, 60, and 80 degree optics.

you can also look at the numbers that Beeker from RC posted. El Camaron also posted some par numbers using the DIY build of chucelli.

If I had the par meter, I'd certainly post them.

[gmubeach]

The club used to have one that you could borrow not sure if its still going on

[Coral Hind]

Z2K, Looking forward to a new FTS of your tank with the new 60's running.

 

 

[fogcutter]

I'm just about sold on these lights. I was thinking of using 2 of the 60 degree on my 57g rimless. I sure wish they were dimmable though.

[chucelli]

El Camaron also posted some par numbers using the DIY build of chucelli.

 

To minimize the amount of already existing confusion and misinformation, let's just make sure we're comparing apples with apples.

The PAR38s have emitters spaced ≈1.5" apart, while El Camaron's fixture design uses a ≈3-4" spacing between emitters with a mixture of 60 and 80˚ optics. They are not driven at the same current, nor use LEDs of the same Bin.

If one wants to see differences in output of the various optics, my original LED thread contains a comprehensive table of PAR readings with varying optics conducted in an environment where all relevant variables remain constant. Also, "Taqpol" from RC recently conducted some very thorough PAR readings of his DIY build, taking coverage into account. It is accompanied by 3D graphs which plot intensity vs coverage using different optics. Since intensity (PAR readings) is directly proportional to coverage with optic changes, it is important to factor total number of LEDs and coverage provided when attempting to compare PAR readings.

-Robert

Edited May 5, 2010 by chucelli