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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Lighting Forum => Topic started by: John Hiemburg on October 08, 2013, 01:16:06 pm

Title: Wider beam spread on Blizzard Propar 74
Post by: John Hiemburg on October 08, 2013, 01:16:06 pm
I'm looking at the propar 74 RGBW fixture, and it appears to be exactly what I need except for the beam angle. I think 25 degrees might be a touch too narrow for my application.


Is there a realistic way to widen it, or can you recommend a fixture in the price range that offers a wider dispersion?


My calculations are putting the 25 degree beam, from appx 14 feet making a spot somewhere around 5.5 feet in diameter - is my math correct?
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: Jano Svitok on October 09, 2013, 05:12:27 pm
I'm looking at the propar 74 RGBW fixture, and it appears to be exactly what I need except for the beam angle. I think 25 degrees might be a touch too narrow for my application.

Is there a realistic way to widen it, or can you recommend a fixture in the price range that offers a wider dispersion?

My calculations are putting the 25 degree beam, from appx 14 feet making a spot somewhere around 5.5 feet in diameter - is my math correct?

My beam calculator says it's 6.2 feet.

Blizzard offers optional 40 degrees optics for the fixture (or at least they say so in the manual).

You may get a bit wider angle by using diffuse/frost filter though I haven't used it.
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: Josh Daws on October 10, 2013, 02:41:33 am
My beam calculator says it's 6.2 feet.

Blizzard offers optional 40 degrees optics for the fixture (or at least they say so in the manual).

You may get a bit wider angle by using diffuse/frost filter though I haven't used it.

if you use silk over diffusion you will get a wider beam spread, and keep intensity up!...
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: Scott Hofmann on October 10, 2013, 10:17:20 am
You could try Elation's LSF (Light Shaping Filter) which is a plastic lens sheet made for LED fixtures that shapes the beam. Comes in 10, 20, 30 and 60x1 degree spreads and supposedly adds the specified degree to the spread the fixture already has (not too sure how true this part is though). Around $100 per gel-sized sheet.

http://www.elationlighting.com/ProductDetails.aspx?Category=&ItemNumber=1705
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: John Fruits on October 10, 2013, 01:29:56 pm
For a more in depth look at why stock diffusion sometimes doesn't work like it does for incandescent fixtures there is this article:
http://www.mikewoodconsulting.com/articles/Protocol%20Fall%202012%20-%20Non%20Gaussian%20Diffusers.pdf
ETC also makes special filters for the desire line, in round, oval and linear spread, but they are all rather spendy. 
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: Scott Hofmann on October 10, 2013, 03:34:50 pm
Well that article certainly explains why Elation's LSF does not work according to their theory: "Effective Angular Output˜ (light source angle)? + (LSF angle)?".
Guess they need to read the article!
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: Kyle Malenfant on October 14, 2013, 01:27:41 pm
I use the LSFilters from American DJ, Elation, Chauvet, etc...

Interesting enough, I've used parchment paper (from the grocery store) on my LEDs when I need a really wide beam angle.  It almost achieves 180 degrees, though there is considerable output loss due to the diffusion, it's worth a try depending on how far the fixture is away from the subject, amount of fixtures you have, and the desired output of each light.
Title: Re: Wider beam spread on Blizzard Propar 74
Post by: John Hiemburg on October 31, 2013, 11:25:18 pm
Thanks for all the tips so far.


I ended up ordering one of the PP74's to just test the real world results. Just at a glance the mean beam seems to be wider than 25 degrees (I'll have to verify the precise measurements), but the beam in general is pretty diffused, so I think it'll work well for what I need.


However, there are a couple of locations on the stage that will certainly require a wider/softer beam because of the ceiling height, so I'll be employing one or more of the techniques suggested above.