How to print a photo for backlit presentation?

Question

I was asked to do an exhibition of some of my latest photos. So far, no problem, but as a highlight I would like to present one photo in a backlit frame. The output size should be something around 2m x 1.5m.

What material is best to print on so one can't see the backlight? Glass or some kind of slide?

Should a slide be glued on an opal glass pane? Such a pane could help to transmit the backlight in a more areal fashion, I think.

What is the best backlight for this? White neon tube or white or even blue LED?

All this seems quite similar to what one knows from bus shelters or those big ads, although in this case the printed picture will be presented indoors.

Answer 1

The best printing substrate would be a translucent polyester film, which is available for large-format inkjet printing in both matte and glossy surfaces. If you have a printer (whether an actual machine, or a service) that can handle prints of that dimension on paper, you're good to go (although it might take some fiddling to get a good colour profile for transmissive illumination). And dyes may work better than pigments for this application if there's a choice; you should get better detail and colour in the shadows with dyes. If you must use adhesive to mount, use it outside of the image area, otherwise the adhesive will telegraph through the image, since the substrate can't be thick enough to diffuse away all of the little differences.

The light box can be a relatively simple affair, using commonly available T8-type fluorescent daylight tubes with a good CRI in "home" fixtures (with a flicker-free high frequency ballast). You can also use a whole bunch of CFL bulbs, but that will be fussier to build and wire. A single sheet of translucent white acrylic of around 1/4" (5-6mm) thickness will even out any hot spots, provided that the box interior is reflective (painted matte white should do fine), and it will be cheaper and less fragile than opal glass. I would suggest simply holding the print against the acrylic diffuser with a sheet of clear acrylic in a "sandwich" frame rather than trying to use an adhesive; there will be a lot less opportunity to harm the image visually or physically.

Do note, though, that this will definitely be a display print with a limited lifetime rather than something with anything like archival longevity.

Answer 2

Well, there are specific materials to print that. It is a type of synthetic paper. But which one to use depends on the plotter you are using. Probably someone can address you to a specific provider, but in my opinion you need to see some printed tests before.

Prepare a sample image, with very dark colors, preferably deep black, and some brilliant colors, a blue sky, a red. And ask for a small size print: Probably a 30cm strip. And see how uniform and brilliant is your print. Then make a test illuminating it from behind.

(Edited. I did not see your picture before... yes it took to long to load!)

But probably you need a specialized provider, because of the large width size you have. In backlite printing you preferably should not have any seams.

You also need to define if you need an outdoor or indoor material. Normally the inks for exterior use have some kind of UV protection.

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For the lighting I would recommend some LED strips similar to this. How close or far apart the series of strips you use depends on how much brightness you need and how deep your lightbox is.

Answer 3

This is something that might require outsourcing and the quality would depend on the depth of your pockets. Duggal in NYC offers custom lightbox manufacturing. If you are going the DIY route using an LED light panel will give you a diffuse source as a start.