Ring Flash Week: Building the HD Ring Flash
So, here's the main structural component of the ring flash. A 16" concrete form tube. ($10.67 at Home Depot.)
This stuff is so useful for DIY goodies. I have seen giant Dobsonian telescopes made out of this. And some killer speakers, too. (No standing waves in a cylindrical design.)
I made this two days after Halloween, if you couldn't tell. More after the jump.
The height of your device will be determined by the length of your lens and body, including shade. Since mine was a tele, I gave the PVC tube a couple of extra inches as a auxiliary shade, so to speak.
You could make this using a wide lens. But the longer it is, the more room for the flash light to disperse inside. And thus, the more even the light on the front diffuser.
I traced a line around the cardboard tube and cut it easily with a jigsaw. I never once made a measurement in the whole process. Just eyeballed, drew the line and cut. As a guy, I am rather proud of that. And it is no loss on your end, as your dimensions will be determined by the camera and lens combo you choose to design it around.
I cheated it a couple of inches on each end (extra PVC for shade and a little extra cardboard tube at the back.) I wanted decent depth for good internal flash throw. Worked out fine.
I traced the tube and the PVC (also cut to length with a jigsaw) to create the donut/washer shape for my front Plexi diffuser. I screwed up the cutting with a jigsaw, so mine had cracks (none fatal) that I had to shore up with clear packing tape. Before taping, I also sanded it on both sides to frost it. (It was not enough, as we saw yesterday, so I ended up with an addition sheet of paper inside for more diffusion.)
This shot shows how the tube and hand-bent aluminum plate brackets mount together. It is important to allow for the bolts in the PVC when checking to see if it will be thick enough for your chosen lens.
If you look at the large version, it should be easy to see how the pieces go together. The camera mounting plate is sandwiched between the PVC and one of the brackets.
You can see the "L" brackets that hold the Plexi to the cardboard tube and PVC here, too. That cardboard tube is tough. May as well be wood.
The bracket assembly bolts to the cardboard concrete form tube, making for a very solid final unit. It went together more easily than I expected.
I think the key is transferring the correct "inner tube" to "outer tube" distance for your aluminum brackets. Get that right, and you are pretty much home free.
Here is the whole thing, put together. The flashes ball-bungee to via two sets of two holes on each side. You'll need a strap, too. Put the strap holes at about 90 degrees apart and it'll ride better on your shoulder. You'll still look like a geek, tho.
You can see the paper disc inside at the bottom here, too.
I used foil-backed tape on the outside of the PVC tube all the way around. This got the light to bouncing around on the inside. I put foil-backed tape pretty much everywhere but near the flashes on the outside. Flashes are fired at the widest setting (W/A diffusers in place) and provide very even -- and strong -- light when all is said and done.
Here is a shot from the front. The light is broad, round and plenty even. I can easily work at modest portrait ranges outdoors in broad daylight, which is great.
It is a little clunky, but hand-holdable nonetheless. Next improvements will be:
• Tripod mounts along both axes -- vertical and horizontal camera orientations.
• Spray paint it flat black, then acrylic to protect it.
• Rounded cap nuts on the protruding (1/4x20) bolts.
• Drop some money on a soft drum case to be able to take it on the road (airlines.)
Here's a photo of the business end, shot by Jeremy Reitman at the Patasco Meetup. I'll be the first to admit that this is a little, uh, gung-ho, compared to some of the earlier designs. But this thing rocks on the output and the even light, so I am one happy camper.
Oughtta have some pretty nice guns by summer if I use it enough, too...
NEXT: Test Driving the DIY HD Ring Flash
New to Strobist? Start here | Or jump right to Lighting 101
Connect w/Strobist readers via: Words | Photos
Got a question? Hit me on Twitter: @Strobist
Save Money: Browse MPEX Weekly Strobist Deals