There are less expensive solutions but before that lets discuss a few kinds of ring flashes and beauty dishes as well as the adapters that try and fill in for a ring flash in various ways by using an existing on camera strobe.
The ring adapters that attach to your camera flash don't create the effect as well as the real thing because of the lower power and defused nature of the adapter which can cause a loss of up to 4 stops. Then again they are less expensive and portable for an "almost ring flash" effect many people are happy with. There are a number of models on the market and it seems theres a new one every few weeks lately. Some models include Orbis, ExpoImaging, Gary Fong, and others.
|Profoto ProRing2 with modeling light 300517 EST. $2695.00|
Orbis Ring Flash Diffusing Attachment EST. $200.00
ExpoImaging Ray Flash Ring Flash Adapter EST. $199.95
Buff 22-inch High Output Silver Beauty Dish Reflector EST. $ 79.95
Another popular solution is a beauty dish like the 22 inch Paul C. Buff, 22HOBD from the makers of Alien Bees, Einstein and White Lightning studio strobes. Paul C. Buff makes this great one that comes with a diffusion screen when you want it and it't large size gives an effect similar to a ring flash but also softer like and umbrella, add in the diffuser and you get an effect like blending a ring flash with a softbox.
I have this beauty dish and find it very useful for fashion shoots in studio or location when I plan on using studio lights. Furthermore, I find myself using it all the time as a fill light and other uses in multi-light studio set ups. It mounts to the same speed rings as all Paul C. Buff lights including the Alien Bees or the White Lightning Pro versions I use.
Build your own for a more useful, lighter, and flexible solution
Years ago I made my own beauty dish, both a shoot through like a ring flash and a studio strobe version using a large metal salad bowl like the ones available at any cooking store or Sam's club or this 20 Qt. version from Amazon.
There are a few important details to consider when picking your bowl. First, you want a large wider bowl, not a deep bowl. The deep bowls are more similar to typical reflectors that come with many studio strobes, you know the ones you promptly take off and replace with a speed ring adapter so you can use softboxs or strip light style modifiers. These deeper bowls would just be like building a flood light and have the wrong effect.
If you have the tools and skills or have a friend who can cut it for you, cut a large hole in the bottom of the bowl large enough to allow you to shoot through the hole. I cut mine to the same size as the hole of my speed ring adapter and used sheet metal screws to mount a speed ring to the back of the bowl, which in turn allows the ring to be mounted to a light stand.
I have two versions of diffusion for the bowl. Both have a thin strip of elastic sewn to the edge so it slips over the bowl one is made of simple white nylon cloth about 6 inches wide so that 4 inches creates a circle of diffusion around the outer edge of the bowl but allowing lots of room in the middle to shoot through.
The other diffuser made the same way only it completely covers the bowl creating a softbox effect. Obviously, you can't shoot through the hole, instead I mount a flash or studio strobe in the speed ring and use it as a round softbox, traditional beauty dish or as a side light.
SInce I used my macro flash which mounts to the front of my lens I simply shoot through the hole in the bowl and basically get the same effect of shooting with a ring light for an investment of less than $30.00 bucks.
I've also seen people make these out of smaller bowls, large pie tins and similar wider parabolic metal dishes.
That worked great for many years of use and I did not have to take too much care to protect the salad bowl from damage on location such as shooting at dusk at the beach, it was so cheap to replace if it was damaged and a lot safer to use around water than studio lights or studio grade ring flashes on location.
Canon Macro Ring Lite MR-14EX EST. $500.00
If you're a Canon user consider the Canon 14EX Macro flash or pick up the Vivitar DF-586 version for less than $100.00 or the Bower SFDRL14C model for the more budget minded. There are versions for Nikon, Pentax, Sony, Olympus and most major camera makers design their own versions too. There are lots of brands of Macro and ring strobes available today. If I was shopping for a new one I would consider an LED version that can also be used for video projects.
Vivitar DF-586 Dedicated Macro Ring Flash for Canon EST. $89.99
So you built one, now what?
Have fun, start with fashion style shoots. Find your favorite muse, sports star, model, kid, or dog and shoot away.
Try using a combination of ring, beauty dish, and traditional studio lighting for a more polished and professional result. Learn to experiment and find the combination that best represents your personal style and client requirements.