Fiber Optic Ring-Flash
Reasoning:
- wanted a ring flash
- already have a 430ex speedlite
- don't have lots of money
- I'm a mechanical engineer with access to a laser cutter
- I'm handy with CAD programs
- I like projects
- Fiber optics might be fun
This page is a description of how i made a ring flash add-on from fiber optics and some acrylic. I had access to a laser cutter to cut out the shapes, but there's nothing so complicated that it couldn't be done with a drill and saw. My goal was to make an attachment for my 430ex speedlite that would make it into a ring-light flash, and to make it rather cheaply. I was inspired by other DIY ring-lighters, particularly this one, and this one.
Materials:
Total: < $100
Plan: I wanted to guide as much light as possible from my flash head into a ring pattern around the lens. I also wanted this attachment to fit on all of my lenses. To accomplish the first part, i figured out the (area of the cross section of fiber optic cable)/price ratio of the unjacketed fiber and found the 2mm stuff to be the best. 2mm is also not too big/stiff. I ordered 100 ft of the 2mm fiber. That hurt my wallet a bit, but it's fiber optics, so it's fun.
Next i checked out my lenses fo their filter sizes. 52mm for my macro, 67mm for my 70-200, and 77mm for my 18-55IS. I ordered some step-up rings from ebay for like 7 bucks each. I ordered a step up ring from each of the smaller lenses to 77mm, and i ordered one 77mm to 82mm ring which will be permanently attached to the ring-flash. Now i can screw my ring flash into any of my lenses.
Design: I had already made a somewhat crude CAD model of my Canon 300D camera and 60mm EF-S macro lens for a previous project. If you use Solidworks or ProE, feel free to download it here in Solidworks2007 format and IGES. (don't make any measurements from it, it's very approximate!). I cadded up a ring with 100 holes for the 100 fibers. This piece is made from the reflective mirror acrylic to evenly spread out the light into the diffuser panel.
I then created the spacer and a front diffusion panel files. These CAD files are used as the pattern for the laser cutter, and the parts are assembled. I also made a front plate for my flash from the mirrored acrylic that has 100 holes for the other end of the fibers. Hopefully the mirror finish will reflect the light around in there until it finds its way down the tubes, that's the idea anyway. There also needs to be enough slack in the fibers so that it can reach to the front of my longer 70-200mm lens.
It turns out that the fibers are quite stiff when bundled, and quite difficult to manage. I found the best way to deal with them was heating them with a hair-dryer so that they soften up a little. At first i planned to have the fiber optics run up through the colored piece and reach up to the flash when it's mounted on the camera, but it seems more and more difficult as i progress. It looks like i'm going to have to have the flash off-camera.
update: It's finally finished, and it kinda works. The lighting is slightly uneven, with more output coming from the side with the bundle of fibers. The bundle lights up a bit more than i'd like as well, so much for total internal reflection right? The last photo on the right shows a test shot of my brother with a decent halo shadow going on.
I hope this little tutorial helped. if you enjoyed it, or didn't, send me some feedback. Also, check out my Photo Gallery, and my tutorial on high speed macro liquid photography. You can also leave me feedback or add me as a contact on flickr.
the end.
