WWOT: Diffuser for Backlighting

RalphM wrote on 2/11/2013, 12:46 PM

Since so many people here have experience with various lighting requirements, I'm posting this question.

I'm helping to mount three stained glass panels indoors. Each panel is 73 x 45 inches and they are positioned together horizontally to form one large "window". (wall mounted) We're trying to achieve very even lighting and it seems that LEDs on strips are the most promising due to size, heat and noise issues.

What would make a good diffuser to go over the lights? We think the panels are too large to be evenly lighted from side mounted strip panels.

Any help would be greatly appreciated.

Comments

farss wrote on 2/11/2013, 1:14 PM

LEDs would be my last choice for lighting stained glass windows. They're very directional light sources. That's why they appear to be very bright.

Easiest way to evenly light your stained glass windows would be with softboxes.
Softboxes of that size are readily available relatively cheaply on eBay from a variety of Chinese vendors. I recall finding ones 72" x 12" so a number of those would work.

Alternatives:
Put a white reflector / bounce behind them, bounce light(s) onto the bounce and put silks just behind the windows

Build light boxes behind the windows and fit a good number of CFL into the boxes.

Note:
They're pretty big stained glass windows and stained glass loses a lot of light. I think you're going to need a lot more light than you realise to get these windows lit well enough to read against the light level in the set.

Bob.

RalphM wrote on 2/11/2013, 8:50 PM

Thanks Bob,
These are going to be permanently mounted, so it has to be a light box type of arrangement. I agree it would be pretty difficult to distribute the LEDs or any light source behind the glass without the point sources showing up. Edge lighting is proably the best if we can span that big of a panel.

Sounds like we're going to have to do several mockups to determine what works best. It's hard to duplicate the lighting of a real window...

Ralph

musicvid10 wrote on 2/11/2013, 9:10 PM

You guys can work out the lighting source; rigid white lucite sheets make great diffusion panels. Expensive, but we went to a plastics company and they donated the panels in exchange for tickets and program advertising. If you're a nonprofit, I suggest that route.

[r]Evolution wrote on 2/11/2013, 9:17 PM

I would think a Diffuser similar to: http://www.digitaljuice.com/products/products.asp?pid=2420

Depending upon your skills... you could DIY.

farss wrote on 2/12/2013, 4:10 AM

If it's permanently mounted then a light box would be the go for sure.
I'm worried that given the size using edge lighting will give you fall off in the middle but if you want to try that then:

Use T5 fluro tubes, you can get them in 6' . They'll give you plenty of light for your money and anyone can service the light box in the future.I'd line the lightbox with Lee 273 Silver Reflector. It's easy to glue on with contact adhesive. Make certain the box has plenty of ventilation. For diffusion on the front use Opal, it's about 80% light transmission. You'll need to pull it tight somehow though. Other alternative would be 1/2 stop China Silk.

Bob.