Getting DIY telecine right: What makes a good diffuser?

Post by **Rollef** » Tue Jul 04, 2006 9:03 am

Hi,

For DIY telecine projects and other stuff you can buy a diffuser from Edmund optics or other online shops.

-What specifically are these diffusers made of?
-What are "opal" diffusers?
-Do they have any different properties than a piece of frosted glass would have?
-What household stuff have you used successfully as a diffuser?

Regards
Knut

Post by **threeinv** » Tue Jul 04, 2006 9:54 am

The semi-opaque plastic used in milk & water bottles would be a candidate for diffusion material...it also cuts very easily. Not sure how it would stand up to the heat of a nearby bulb?

--Derrick

Post by **VideoFred** » Tue Jul 04, 2006 11:28 am

I did many tests....
I tried everything you could think of.

I have the best results for now with a reflector at 30-45Ã‚Â°.
Like Christoph already mentioned, the angle is less important.
The distance between the lightsource and the reflector is important.

I have made a setup with Luxeon Leds and it works very well.
The benefits of this system:

- no heat..correction.. low heat compared with traditional bulbs.
- very good light spreading
- very good and vivid color reproduction
- very sharp picture
- less blown out whites

The system itself already gives less blown out whites,
but Leds can be dimmed very accurate, too.
You can realy set the amount of light at the ideal point.

If I ever find the money for it, I try this one:
http://optoelectronics.perkinelmer.com/ ... tID=ACULED

They have this very interesting evaluation kit:
http://optoelectronics.perkinelmer.com/ ... Dflyer.pdf

Now, with this kit we can control the backlight intensity AND color with the computer!
It is even possible to save the settings (for different filmstocks!)

The price of this kit is 250,00 Euros

It is available in Belgium

Mama I need money :oops:

Fred.

Post by **gianni1** » Tue Jul 04, 2006 5:35 pm

I used the white plastic diffuser removed from a small handheld 35mm magnified slide viewer. It's a the part that goes between the slide and the light bulb. It won't hold up to hot bulbs, but it's ok with lamps a few inches away.

Gianni

Post by **onsuper8** » Tue Jul 04, 2006 5:52 pm

There's many ways to skin this cat! I used a proper opal diffuser which does what it says diffusing the light source, but I'm with Fred, the more diffused source you can start with (multi LED's - light frequency issues aside) the better. With an opal diffuser you still need to dramatically reduce the wattage to prevent any chance of hot spots still being evident. I'm presently on a 10W source with opal diffuser and not really having any issues.

Post by **Rollef** » Tue Jul 04, 2006 6:59 pm

I stopped by the electronics store today.

http://www.elfa.se/en/

and ordered a diffuser. Will have that tomorrow and test it. Am not happy with the results I get with "frosted" plastic screens. The picture is "whashed out". I changed from 20 watt halogen to 10 watt bulb, and that seems to help some, so hopefully the diffuser will do the trick.

They also had the Luxeon 3 watt, and came up with a solution to use the 12 volt power via a doohickey + a potentiometer to make a variabel LED. That would be nifty, and if I am not happy now I'll persue Videofreds LED alternative.

Fred,
What powersource do you use for your LED and have you added cooling?

Post by **Rolle_B** » Wed Jul 05, 2006 2:01 am

Hello Rollef

Try this:
http://forum.voodoofilm.org/showthread.php?t=9008

It works great!
Rest of you, sorry for no english text, but the same is described in VideoFreds "New R8 unit" on page 3.

Post by **Justin Lovell** » Wed Jul 05, 2006 5:13 am

"LeeLux" diffusion, good stuff. Can be found in the cinematographers edition swatch book by LEE.

I double layer the stuff infront of my LED source.