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Monday, June 25, 2012

What Sized Soft Box Should I Use?

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Every year, the OctoDome® series of modifiers is used in hundreds of thousands of fashion shoots, editorial spreads, wedding photos, and portraits. It’s impossible to recognize what size of OctoDome® was used in a finished image without becoming familiar with what each one does.

This lesson by photographer Ben Clay gives you an objective comparison of several sizes, with a clear explanation of each example. As you’ll see, each OctoDome® has its own characteristics. Ben goes on to demonstrate how OctoDomes of different sizes can be used for the key, fill and rim light. When combined, the results are beautiful, professional and easy to achieve. You’ll be able to put this information to work right away!

Choosing the Right Sized Soft Box

I often get asked by people just starting out with lighting, "What sized soft box should I use?"

It's a really good question! My short answer is usually something like, "Personal preference aside, it's important to understand what each sized soft box does. A very small soft box will provide directional, high contrast light, whereas a very large soft box will provide a broader, softer quality of light. And the closer your soft box is to your subject, the softer that light will be."

The long answer, on the other hand, involves demonstration. And so hopefully this lesson will help!

For this shoot, I wanted to demonstrate a range of main/key light options, as well how one might want to add on to that main light. The lights I used here ranged from a bare on-camera pop-up flash to a portable TritonFlash™ strobe with a 7-foot OctoDome® soft box attached.

The Built-In Flash

"Built-in flash" refers to the permanently attached flash or "pop-up" flash that’s used for a high percentage of casual indoor snap shots. It's typically built into the camera and therefore always with you, it's easy to use, and it can certainly help with exposure levels.

The problem, however, is that it's a very unnatural-looking quality of light. The same goes for bare shoe-mount flashes, but to a slightly lesser degree. Because this type of light is so small and typically projects light in the same direction that the camera lens is pointing, it tends to flatten out the dimensions of your subject. It can also cast distracting shadows behind your subject, and if the light and lens are close enough to each other, your subject will end up with red pupils (which is only beneficial if you happen to be shooting someone in spooky Halloween garb).

Here's an example of what I've just described. To start, I asked my model, Kim to stand in front of a portable wall corner in the studio for a series of shots. With my camera set to Auto and the pop-up flash enabled, I took my first shot. 

Although the exposure levels in the result are fine, the quality of light is less than flattering. The flash flattens out Kim's features, casts a hard shadow directly behind her, and renders noticeable red-eye. We're all familiar with this type of auto snapshot result, and while it’s better than no photo at all, it’s certainly not the best one can do.

Hard Light, Off Axis

Next, I decided to mount a portable strobe to a LiteStand and position it off-axis to the camera to demonstrate the difference in dimension. I used the TritonFlash™ head and continued to use this head in this approximate position with different accessories for the remainder of the shoot. To start, I attached a 7-inch hard reflector to the head, raised it up about seven feet, and angled it toward Kim.

I used a wireless kit to be able to sync the flash with the shutter and I set the power to the TritonFlash™ to about 1/16th power. Here were my camera settings:

  • Exposure Mode: Manual
  • Aperture: f/8
  • Shutter/Sync Speed: 1/125th of a second
  • ISO: 200

Once everything was synced up, I took a few shots. Here's one from that series.

Though the size and quality of light was similar to the pop-up flash, the result was dramatically different, mainly because of the off-axis projection of light. Notice how Kim's facial features are rendered more dimensionally than before and that there is no glaring shadow directly behind her. Instead the shadow is off to the left, but not as hard as the result with the pop-up flash, thanks to the parabolic shape of the 7-inch reflector. The closer shadows, cast from Kim's nose, chin and dress, are still quite hard.

The XS OctoDome

Next, I replaced the 7" hard reflector with an XS OctoDome® soft box, the face of which is 1.5 feet in diameter. I kept the light head in the same position, but opened up my aperture to f/5.6 to accommodate the stop of light with the diffusion material over the light. As you'll see, the OctoDome® would help to diffuse, or soften the hard quality of light from the flash head. 

Here's an outtake from the next series of shots. 

Notice the difference? The light is still traveling in the same direction, but the XS OctoDome® has toned down the harshness somewhat. Notice how the shadow under Kim's chin is a little softer than in in the previous result.

The Small OctoDome

Next, I replaced the XS OctoDome® with a Small OctoDome®, the face of which is 3 feet in diameter. Even from the setup shots, you can see how much softer the shadows are rendered. 

With no change to the camera settings, I took a few more shots. Here's one from that series. 

As the soft box gets bigger, you can see that the lighting gets softer. At this distance, the Small OctoDome® does a good job of lighting Kim evenly, while still maintaining a directional feel. The light is definitely softer than with the XS OctoDome®, but it wouldn't be considered "wrap-around" lighting.

The Medium OctoDome®
Next up was the Medium OctoDome®, the face of which is 5 feet in diameter. As you can see from the setup shots, the shadow cast from Kim is quickly dispersed to the point where it's barely noticeable on the back wall. 

With still no change to the camera settings, I took a few more shots with this setup. Here's one from that series. 

As you can see from the result, the jump is pretty substantial. This Medium OctoDome® is so wide in comparison to the Small OctoDome® that it's able to throw light from wider angles and fill in areas that would otherwise be in shadow. The transitions from light to dark are now smoother, yet there is still a sense of dimension to Kim's face. Soft light, yet directional.

The Large OctoDome®

Finally, the Large OctoDome®, with a diameter of 7 feet. This soft box is big and beautiful and is ideal for lighting subjects evenly from head to toe with soft, diffused light. 

I maintained the same camera settings as before, but then increased the power on the flash to 1/8th power to accommodate the larger box. Once it was in position, I took a few more shots. Here is one where I was slightly left of where I had been before. 

Even though I captured this image further left of where I had been before, the effects of the Large OctoDome® were still noticeable. The catch-lights in Kim's eyes here are much larger than they were in previous shots and there is almost no shadow under her chin at this point. This light is so broad that the whole right right of her face (camera right) is all pretty much the same tone. This can be flattering for some faces and not so flattering for others. Each person's face has a unique architecture, and therefore requires different treatment when it comes to lighting. But you also have to factor in personal preference. Some photographers prefer soft, broad lighting, while others are drawn to more contrast. Knowing which lighting tool does what, however, helps you to define the look you're after.

Comparisons

Here's a side-by-side look at all of the main light result shots I captured during the first part of the photo-shoot. 

For the second part of the shoot, I went back to the Medium (5-foot) OctoDome® and build the rest of my lighting upon that. I also angled the OctoDome® a little further to the right so that it wasn't so top lit as before.

Adding More Lights

When you're first starting out with lighting, it's easy to want to throw a lot of lights in a given shot. The thought being, the more lights you use, the better quality the image. More often than not, this is not the case. I've come onto sets where there are six or more lights being used, and most of the time it's overkill. Too many lights can kill the dimension of a shot if you're not careful. Attempting to fill every area with light will only result in flat, dimensionless images.

That said, a couple of additional lights strategically placed can enhance, and even magnify, the sense of dimension in a shot. One of the best ways to do this is to add rim lights. As the name suggests, rim lighting creates a highlight along the rim of your subject, helping to separate her/him from the background. Rim lights must be placed slightly behind the subject so the beam of light hits the outer edge, but never the front of the model. The result of a well placed rim light is one of the best ways to elevate your shot from a pleasant look to a professional look. These lights also help to articulate or define the shape of your subject.

Often times, hard reflector lights are used for rim lighting, but there are instances where this approach is too severe and highlights can become too textured or overblown. Rather than use hard reflectors for the rim lights in this session, I opted for the smaller OctDomes I'd used previously. First, I set up another strobe, attached the XS OctoDome® to it, and placed it to the rear of the set, camera left. I also angled it so that it would cast a shadow along the right side of the movable wall to make it more interesting. With another wireless receiver attached to this new head, I turned off the receiver to the main OctoDome® to see the effects of this rim light set at 1/8th power. 

Next, I set up another strobe, also set to 1/8th power, but with the Small OctoDome® attached. I then placed it on the other side of the back of the set. Once that was angled properly, I tested it out without any of the other lights going off. 

Lights, Box Fan, Action

For a final touch, I had my assistant, Cameron, stand on a step-stool and aim a box fan at Kim to simulate a gentle breeze. Great for hair.

After a few test shots, I was ready to go. Kim had been very patient with me with all of the example shots, and I sensed she was ready to give me some different poses. This was actually her first studio photo-shoot, and I could tell she was a little apprehensive with "posing". Nevertheless, we shot for about 10 minutes or so and got some really great results. Here's one of my favorites of the shoot. 

As you can see from the result, the rim lights helped to give shape and definition to Kim's features, yet did not overpower the soft effects of the main light. I felt this was a good balance of lights for Kim, and in the end, she looked like a seasoned pro!

Conclusion

In response to the question posed in the title of this lesson, “Which OctoDome® should I use?”, I offer up the following: Any size OctoDome® will be a dramatic improvement over on-camera flash or unmodified raw flash. As mentioned earlier in the lesson, the bigger the light source, the softer and more natural looking the light. Additionally, the closer you move a soft box to your subject, the more soft wrap-around light you’ll achieve.

For my purposes, I tend to select a size based on the characteristics of my subject, as well as the look I'm going for. For this reason, it's nice to have a few options. But if I had to choose just one OctoDome®, it would probably be the Medium (5 foot), as it's incredibly versatile.

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Photographed and written by Ben Clay, contributing Instructor for PhotoflexLightingSchool
Modeled by Kim Sprague
Assisted by Cameron Rockwood

Lighting Equipment

Comments

On June 25, 2013 at 10:46 AM, Paolo Cinra said:

Great lesson, thank you!

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