This is the final post in my series about my DIY Macro Ring Flash light modifier. I'd recommend reading the Introduction first, then the Construction, then this post. To refresh your memory, this is what I'm working with:
Depending on the shot, the lens I've used is either a Canon 50mm f/1.8 prime, Nikkor-H 50mm f/2 (reversed for approx 1:1 macro), or Tamron 17-50mm f/2.8 (above). Wherever possible, I've noted the shooting parameters. Of course, I've had a real hard time remembering what I set my flash power too, so those all have implicit question marks next to them. All were taken with a Canon 20D. And of course, click to see them larger.
Analyzing the Light:
The first step is to really analyze what sort of light I get from ring flash, and more specifically my ring light construction. As Strobist says, ringlight is a bit cliche in high fashion modeling circles. I mean how many pouty models can you really look at with that halo shadow on the wall behind them (actually, I can look at quite a few without getting tired, but...). To demonstrate the effect, I shot my trusty wedding cake topper in front of the wall (Canon 50mm, f/6.3, 1/250s, ISO100, 1/4 power). There you go... cliche ringflash shadows.
Ultimately, a ring flash is simply an area light located on the lens axis. Move it off the camera, and it is essentially a soft box with a hole in it. In the case of my macro version, the area is pretty small (maybe 6 inches in diameter). So if the ring is large compared to the subject, you get the nice soft halo shadows (due to light from each side going around the object) and the brightest part of the object is normal to (facing) the camera. Also, you get a really nice, slow, roll off of light around the subject with some wrap-around light.
But, if the ring is small and/or far away from the subject, the wrap-around light is lost and the ring light acts as an on-camera flash exactly on the lens axis. For instance, the image at left I used the ring flash as fill and it gives slightly better results than on-camera flash because the light is coming directly from the lens, not 3 inches above it. It also helps that the total area of the ring flash is much larger than an average on-camera flash which makes a more pleasing fill. (Tamron @ 20mm, f/3.2, 1/30s, ISO400, 1/2 power)
When it comes down to it though, this flash modifying contraption really isn't meant for human subjects (although it works well as fill light). It really won't give a different look than a small on-camera flash and it lacks the punch to really light up a room (the light path and diffuser eat a ton of light, something like 4-5 stops by my estimation). At 400 ISO you can get it to cover maybe 6 feet. If you are serious about getting cover of full bodies, you'll want to look at a beefy ringlight like the Strobist ring flash. My flash does work pretty well on faces though as long as you are pretty close and fill the frame (sorry, I don't have any flatterying face photos yet).
It was designed for macros, so that's what I'll discuss next.
I'll admit it: I like to chase bugs and animals around the yard shooting macros. And that's why I built this thing, because it is nearly impossible to not blur a 1:1 macro at f/16 in natural light shooting handheld without going to ISO 1600 (which introduces more grain than I can safely smooth out). Plus, at a macro level, a 6-inch ring flash is a monster and gives a great wrap around look.
While I don't have many images I'm super proud of just yet, I've got a few macro examples from when I was playing around with the thing a few days ago. I'd have more, but it has gotten really cold around here lately (60s during the day, high 30s or low 40s at night) and the bugs are harder to find. Soon though!
First up, the required bee shot. Not my best (especially because I had to be inches from the thing and it was moving enough to make me nervous). In this case, I left the motor drive on and let it take a shot without the flash afterwards to show you the difference.
(reversed Nikkor-H 50mm f/2,
1/250s, f/16, ISO 400, 1/2 power)
A few notable things. First, I'm overpowering sunlight, which was one of my goals from the beginning. The sunlight is probably two stops lower than the flash, but it still gives a nice highlight to the wings (note how the natural light image at right exhibits a bit of blur even at 1/250th!). While it takes about all the power my flash has, it is nice to know that I have the flexibility of not depending on the sun as my key light. It is still a bit tricky to find the right balance between shutter speed and flash power, mostly because of the blur at these levels.
Second, I can get the shot at f/16, which is a huge pleasure. I finally can stop struggling with the smaller depth of field that the larger apertures leave me with. Between the action-stopping power of the flash and the larger depth of field, I'm getting great sharpness from my $20 Nikkor-H. Not bad for something I made for free.
Ok, almost done. Next up, I have the lower portion of my fuschia (stamens and pistils). The real thing to note on this image is the staggering sharpness of the waterdrops in the upper left (too bad I focused slightly behind the flower) and the beautiful wrap-around light on the stamens).
(rev Nikkor-H 50mm, f/16, 1/125s, ISO 400, 1/2 power)
Finally, another nice thing about the ringflash is it lets me go mobile with higher magnification than 1:1. For instance, I slapped some extension tubes on the lens and tried to chase a few things around (ants move really fast at 2:1!). The subjects that moved slow enough were these baby snails, which are actually quite tiny. This image is almost the full frame!
(rev Nikkor-H 50mm, ~20mm extension tube, f/16, 1/125s, ISO 400, full power)
Ok, hopefully by now you get what the macro ring flash adapter can do, and what it can't. Like many people hope, it isn't going to revolutionize your photography overnight, but for macro work (or a large enough ring at human-scale) it can really add a new look. Futhermore, the design is very handy; I slap it on the camera and it stays with me, leaving the camera very maneuverable (I used a little strip of scotch tape to hold it on). And if I don't want to use it, I'll turn it off and flip it out of the way with the tilt option on my Sunpak.
Yes, I'd love some more power, but for macro work, it has plenty of power (and isn't too powerful, as in the case of the bare flash at 1/16th power). Larger would be nicer too, but a larger flash will but more stress on the hot shoe and result in more light drop-off in the ring. As it is though, the paper is super light so I don't worry about hurting the flash or my 20D's shoe.
So, if you have some time, try to whip one up. Once I've spent more time with it, I might build another, more improved version. For now though, I'm quite happy and it will be just one more photography tool I keep around!