Getting the most from your parabolic umbrella
It has been a few years now since Paul Buff (Alien Bees) introduced their 86-inch PLM (Parabolic Light Modifier) umbrella, which was quickly followed up by similar umbrellas from other companies. Some call them a 7-foot umbrella (measured across the arc of the back of the umbrella), some call then 65-inch umbrellas (measured across the opening of the umbrella). They come in a variety of styles—white reflective, dull silver, shiny silver, and translucent (shoot through). They have 16 ribs/panels (most photo umbrellas have 8, while the Photek GoodLighter and Softlighter have 10). The more ribs, the closer the shape comes to being round.
But it is not just about the shape (mostly noticed in the catchlights of people). Before all of these inexpensive parabolic umbrellas there were others at much greater price from companies like Broncolor and Briese. I believe it was all started by Briese, but their market is mostly in the film industry. More photographers around the world are familiar with the Broncolor Para modifiers that come in a variety sizes from their Para 88 (about 3-feet across the front) to the Para 330 (almost 11-feet across the front opening). Prices range from $3,000 to $7,000 or more just for the umbrella system.
These original parabolic reflectors provide a wide range of looks by having a mechanism to move the lamp head within the umbrella to focus or defocus the light. With the lamp placed deep into the umbrella you can find the focus spot that turns it into a gigantic spotlight that collimates the light rays emerging from it. But many people feel that the real beauty from the para comes when it is defocused. To do that bring the lamp head all the way out to the edge of the umbrella. With its 24 shiny silver panels the center of the umbrella goes dark and you wind up with 24 small bright spotlights around the edge, making it into a gigantic ring light.
It is this soft, yet hard, ring light quality that I have found to be lacking in the 7-foot class parabolic umbrellas. For most of the time that I have owned these big umbrellas I have basically used them as umbrellas for fill light or with a heavy diffusion fabric across the front turning them into big round softboxes. That is fine for the white reflective and the translucent umbrellas. But that silver umbrella. There had to be more to it.
For the photos in this article I will be using the shiny silver version of the Interfit Photographic 65-inch Parabolic Umbrella with their Honey Badger studio flash. You can slide your lamp all the way in on the shaft of these umbrellas to create a strong spotlight like effect. But drawing the head out to the end of the shaft doesn’t get to the ring light look. Take a look at the first two photos of the silver umbrella with the head all the way in making for a concentrated light and then with the head pulled out to the very end of the shaft. The center is still the hot spot in the umbrella. Where are those spotlights around the edge of the umbrella?
For a while I’ve been thinking about ways to make these umbrellas act a bit more like the Para. I don’t expect to match it exactly, but I was sure that I could do better than what I’ve been getting. It finally dawned on me to take the lamp head off of the umbrella shaft and mount it on a separate light stand so I could pull it even further out of the umbrella. Take a look at the light pattern in the umbrella in the third photo where I have placed the lamp 5-feet (60-inches) from the center of the umbrella instead of at the 31-inches when mounted on the umbrella shaft. This is starting to look more like what I’ve been trying to achieve. The edge lights are not quite as small as I would like, but I think that comes from the overall shape of the umbrella. The true paras are deeper and more of a cone shape than the 7-footers.
What does all that translate to on the other side of the camera? Here are three self portraits made with the lamp head in the three positions. The modifier and camera remained stationary between these photos with the umbrella about 8-feet away from the subject and white seamless paper about 2-feet behind the subject.
The first image feels a bit harsh and contrasty for my taste. The second is a little nicer with a bit more of a feeling of the light wrapping. Third image is my choice for contrast and quality. Notice the color change in the third photo. In the first two images the light is pretty well contained within the modifier and doesn’t bounce all around the room (what I call environmental bounce). In the third image the flash head is well outside the modifier, as shown on the right, bouncing light around the room which has a golden colored wood floor, which becomes a secondary light source, which warms up the image considerably.
Here are closeups of the catchlights in each of the above. Some might find the ring light look in the third image distracting. Other people might not ever notice it.
With the lamp head way out in front of the modifier you need to be careful about the light striking the front of the lens causing flare. The lens hood might not be enough. You might need to set up a flag between the light and the lens depending on how close you are trying to get the light to your subject.
You can stop reading here if you like. But if you want to geek out a bit about parabolas, I’ve added the following section.
Going more into the geek…
Let’s look at what makes a parabola. First the standard definition: a symmetrical open plane curve formed by the intersection of a cone with a plane parallel to its side.
Basically, it is a U-shaped curve. You can read tons more on Wikipedia. Here we are concerned less with what a parabola is or how it is formed, but more about what it does to light. Within the parabola is a focus point on the axis of symmetry and outside is a line called the directix. The parabola is the shape defined when all the points on a line are equidistant from both the focus point and the directix. Visually, it goes something like this on the right.
When talking about light, a (theoretical) point source placed at the focus point is reflected into a parallel beam, leaving the parabola in parallel rays. In actual practice let’s just say that the light is deep (falls off slower than inverse square would predict) and contained or directional. Various factors prevent the light rays from being truly parallel. There is little environmental bounce, so the light is contrasty, but it is also large, so it fills in some shadows. You will need to experiment with having the light at different distances from the subject to find the look that you like.
If the lamp is moved further out of the parabola—defocused—the light rays are scattered (diffused) and exit in a diverging pattern, but the center goes dark and you get a ring of bright spotlight-like lights around the edge of the reflector. The overall exposure will be less as more of the light is spread out and bypassing the subject. Again, experiment with different light-to-subject distances, erring towards having the light closer in the smaller the parabolic umbrella you are using.