OT: Backlighting stained glass window

[pdavid]

Hello!

I have the following situation; my church has a large, round stained glass window (96in diameter) would we would like to illuminate at night, so it can be seen from the outside. We are looking at an electric light that would make the stained glass visible from the street.

The first attempt, a couple years back, was to place a single flood light 15 feet behind it, and turn it on; well, from the outside, it looks like there is a single light bulb behind the stained glass window, very bright, and the rest of the window is much darker. It does not look good, to say the least. Forward to today, where the problem landed on my lap.

I am thinking of a way to diffuse the light so that it does not look like there is a single source (or multiple sources) of light behind it. I'd like to have the light as uniform as possible.

I DAGS and a search in rec.woodworking, and all I have found were ideas for smaller windows, for which a single light would b appropriate. I know that churches in Europe illuminate their stained glass windows and that it looks really nice. What is it that they are doing right and that I do not know how to do?

Thanks in advance.

Pierre

[Malcolm Hoar]

Well, I've never actually done this but... I think you need to light the inside of the church (and not the window). In short, use the walls, roof, floor and the contents as a giant reflector. Then you'll get a glow through the window.

Trying to light the window directly would be a disaster but you already know that ;-)

I think it will likely take a lot of lights and a lot of power to create a really good effect however.

[Leon]

Rope Lighting

[RBM]

I don't have the answer, however years ago I did electrical work on a church renovation with a world renowned company called Rambusch. Lighting is one of their specialties. It may be possible to contact them and ask a few questions. They're located in NJ, you can find them with a google search

[Lew Hodgett]

RE: Subject

Use 15W flood lights 12"-18" apart depending on how far way from the window the lamps are located (bigger is better) Start with maybe 3 ft.

Use 600W dimmers with alternate lamps on a common dimmer. That way you can control overall illumination and shading at the same time.

This is a total PITA job that will require a lot of evenings playing around before you are satisfied.

Lew

[Pat]

In photography, if you want soft, even lighting you use a "soft box". Often it is a fluorescent light shot into a diffuser.

If I were trying it, I would follow the same principle. I would but a piece of frosted plastic or plexiglass a foot or so inside the window. Then behind it I would position a number of compact fluorescent lights space apart a bit.

If that didn't work, I'd construct a "shadow box" behind the window a few feet. I'd paint the back wall a bright white. Then I'd ring the wall with fluorescent tubes to light it up. Then you'd be looking through the glass at the white wall, not at a light.

Good luck with it.

[Noozer]

Instead of using a single light source, try three or so... and not directly behind the window, but off to an angle.

[pdavid]

Wow!

Thank you very much for a number of very good suggestions. I very much appreciate the time and effort you took to respond!

Thanks again!

Pierre

[Old Guy]

Another suggestion--talk to an architectural electrical engineer/ lighting engineer. They deal with this all the time, and could make suggestions that would look professional instead of homemade. Also might be quicker.

Might cost a buck or two for the consultation, but if you didn't take much of their time, they would try to keep it modest.

Ask a commercial electrician to recommend an engineer that does this sort of thing well.

Good Luck!

Old Guy Who was an architect in his past life.

[Lew Hodgett]

An Update:

Use spring clamp lamp holders to make positioning the lamps easier.

Use a distribution strip with 6-8 outlets to plug the lamp holders into, then connect the distribution strip to the lamp dimmer.

Costs a few $, but less than a lighting designer would charge.

The above provides lots of flexibility.

Lew

[Mark]

you might talk with a photographer and see if you could borrow some reflectors like they use to defuse light for portraits. Perhaps bouncing your spotlight off one of these would give a more balanced light than the straight light against the window.

[Warren Weber]

Pat has the best Idea. I made a light box for photo slides. Bought some Plexiglas from a glass company. It is white but translucent. Put fluorescent lights under it. works great and no heat problems. W W

[Malcolm Hoar]

Personally, I don't think the impact on the inside view of the window would be unacceptable. But...

rather than use frosted plastic, one might be able to install some kind of roller blind make out of a white translucent material (ripstop nylon works). This could be lowered at night (to enhance the outside view) and raised during daylight (to minimize the adverse effect on the inside view).

It might just work.

I've made my own photographic softbox using some cheap fabric from Walmart and it's great.

Bouncing lots of light off the inside walls/roof is more likely solve the OP's problem, in my view.

[Robatoy]

Frosted mylar would roll up and be cheaper.

[Pete C.]

Go to

and look at their various diffusion materials as well as their rear projection materials. Basically you want effectively a roll down window shade on the wall inside to cover the window at night with the shad made from a suitable diffusion material to even the light and hide the point source. The point source should also be located so that it is not in line with the primary viewing axis from outside, likely a couple floodlights positioned relatively low and to either side of the window and of course the 15' back.

[George Anderson]

A 250-500 watt 6" fresnel theatre light with a diffusion filter and barn doors should do the trick. Add a light dimmer and you should be good to go. The fresnel has a focus adjustment that will allow you to control the spread. If the spread is too much then an elipsoidal (leeco) theatre light would be the next option. Contact an outfit that rents theatre lights and rent a light to give it a try. For diffusion filters and possibly adding a colour filter to make the light warmer or cooler have a look at the Rosco or Lee filter swatch books. The theatre lighting store should have some sitting around.

George Anders> Hello!

[pdavid]

I must say... Thanks very much for a number of very good ideas. I will start experimenting, from the easiest alternative to the most expensive, and I am pretty sure that one of them will work.

Thanks a bunch!!

Pierre

[Norminn]

A good lighting store should be able to help you. Need to know the elec. capacity, location and distance of fixtures, etc. Floods are probably the answer, as they are available in so many different brightness and spread levels. It seems likely that some level of light, in addition to the floods, would be necessary in order to eliminate the "one bulb" look. Seems you could rig a test, using just an extension cord, receptacle and various bulbs to get an idea of what works. A less-bright bulb, along with the right reflector, might give the right diffusion for the task.

[FatherAlphonzo]

My son, You already know the answer in your heart. You must pray to God to ask him to place a small sun inside the church. This would be a natural, solar powered sun, so no electricity is needed. Once the sun is delivered, place it behind the window and protect all flammables from igniting from the heat of the sun. Your light will shine on the town and inspire everyone in your town to attend your church.

Father Alphonzo III

[whit3rd]

Best illumination for a stained glass window is northern exposure, on a cloudy day; you want a diffused light background. Unless you don't want to admire the window from INSIDE the church, it has to be nonblocking from the interior.

Two solutions suggest themselves.

(1) Unpleated sheer curtains with electric control, that draw back in the day but close and glow under diffuse backlight (a bank of fluorescents, if the colors can be made to work, or halogen if not) during the evenings.

(2) if the line-of-sight from the ground is through the window to a ceiling, apply suitable reflective paint (like used for painting surfaces for projection screens) to the ceiling and illuminate the ceiling from light sources near the window inside the church, aimed at that ceiling surface. One can hybridize the two, using a motorized reflective-screen.

A third possibility is ... amusing, but maybe not practical. If you could commission a Fresnel lens and sandwich it against the stained glass, it would be possible to use the single-point-source illuminator inside and still get whole-pane brightness in some suitable viewing zone outside (near the virtual focus of that source). I actually used this trick once, to make a microwave oven display more visible at an odd viewing angle.