Tuesday, September 29, 2009

Fiber Optic Ring Flash

I was inspired by Joris van den Heuvel over at Fuzzcraft with his experiments building fiber optic ring lights, so I decided to make one myself. It's made completly from parts and materials that I had laying around:

* main ring -- 3" ABS pipe
* fibers from a toy lamp
* 4-40 screws
* cardboard forms made from a cereal box
* epoxy to hold the fibers in place.

The hardest part was drilling all the little holes in the ABS pipe for the fibers. They're only about 0.5mm, and if you've every tried to drill small holes in plastic, you know how easy it is to melt the plastic and mess up the hole. I ended up drilling slowly, clearing chips often, and with lots of water for cooling/lubrication. Once I got I the holes drilled, I discovered that the fibers varied greatly in size. Since the holes varied a bunch, this worked out fine, but it took some time to match fiber size to hole size and made for an uneven light pattern, as you can see in the reflection in my sister's pupil:

My sister's eye -- hand held, daytime, indoors
D300, f/10, 1/60s, ISO-400, AF Micro Nikkor 60mm 1:2.8

Once the fibers were in place, I poured on epoxy to hold it all together. This worked fine, but was a bit messy. Once the epoxy was all cured, I ran both ends of the fibers on a belt sander to flatten them out. They still need polishing for best results. Even so, it's functional, at least for macro photography. It's not currently bright enough for more than a few inches away, so it's not great for portraits yet. And, the fibers definitely do not all transmit the same amount of light. Some are too small, while others are either bent too tightly or were damaged in construction. Nonetheless, it's working, and I'm happy to be able to take hand held macro shots in low light:

Garden spider -- hand held at night
D300, f/10, 1/60s, ISO-200, AF Micro Nikkor 60mm 1:2.8

Crested gecko -- low light, indoors
D300, f/16, 1/60s, ISO-800, AF Micro Nikkor 60mm 1:2.8

Other than needing polishing that I mentioned above, I'd like to paint it -- maybe silver underneath with a flat-black top coat. Currently, I use a piece of aluminum foil over the top to help get light into the fibers and keep it from going straight through and washing out the top half of the shot.

Next time, I'd use higher quality fibers, position the holes better, and try to get more even light.

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