Softboxes

Today's post comes from the Softbox Lighting Techniques for Professional Photographers by Stephen Dantzig. It is available from Amazon.com and other fine retailers.

Softboxes are a specific type of light modifier. They are designed to produce an even spread of light from all parts of the box. Your light fits into a housing that you use to attach the softbox. The housings will be different depending on your strobe or hot light. The number of connectors will also vary according to the shape of the softbox.

HOW THEY WORK
Softboxes work by spreading out the light from what would be a small specular light source. Softboxes are designed to go from narrow by the light to as broad as the outside dimensions of the softbox. The inside of softboxes are lined with highly reflective fabric—oftentimes bright silver. As the light travels through the expanding corridor, it bounces around the inside of the box, reflecting off of the fabric in all directions. It is no longer a spot source of light by the time it reaches the outside diffusion material. Rather, it becomes a wall of light that is equal at all points. It is this wall of light that is further diffused as it passes through the outside diffusion material. Note that you can use different-colored panels to line the inside of your softbox to change the color of the light illuminating your subject.

There are usually two sets of diffusion material that the light waves pass through before illuminating your subject. The first is known as a bevel. This is a thin piece of translucent white fabric that attaches to the inside of the softbox. This material is usually fairly close to the light and provides the initial diffusion. The now diffused light continues to travel through the softbox until it hits the outer translucent white material. The outside dimensions of the box determine the size of your light source, creating a larger (and hence softer) light source than what you attached to the softbox. Furthermore, the light leaving the softbox is diffused twice, and this softens the light even more.


The double diffusion design of the softbox yields a beautifully soft light that is perfect for beauty headshots. The quality of light will differ depending upon the size of the softbox, but it will still be softer than the spotlight. In this case, a 30x40-inch softbox was fitted with a Circlemask to create this beauty image of Midori Every. The Circlemask creates round catchlights that look natural. The main light was metered at f113/10 with a silver board in place to bounce light back under Midori’s chin. Two medium StripDomes were used as hair lights. The image was exposed at f11—1/3 of a stop overexposed.

The inside bevel is just one of the things you can modify to change the effect created by the softbox. Here, we removed the inside bevel and created a beauty image with a little more “pop” than we had with the bevel attached. The new exposure was f117/10, so the inside bevel “eats” almost 1/2 a stop of light! We turned down the strobe to f113/10 to make the exposure the same as the shot with the bevel. The light is still soft enough for general use, and the technique may help if you do not have powerful strobes and you need all the output you can get.

WHY USE THEM?
Light, in most cases, needs to be diffused before it will give you a pleasing photograph. Spotlights can produce very dramatic fashion images—partly due to the harsh quality of light, but also to the repetitive shadow patterns that can be created. However, diffused light has many more applications.

HOW TO USE THEM
Every light source has an “ideal” distance that allows you to maximize its design. In the case of a rectangular softbox, you use the Pythagorean theorem to determine the theoretical distance that will optimize the contrast of the box while maintaining its quality of light. You would have two right triangles if a rectangular softbox were dissected along its diagonal.

The theoretical ideal distance would be the hypotenuse of the right triangle. The Pythagorean theorem tells us that the hypotenuse (C) is obtainable via the following equation: A2 plus B2 equals C2 . Let’s assume that A=40 inches and B=30 inches for a fairly standard 30x40-inch softbox. A2=1600 and B2=900, so C2=2500. The hypotenuse, C, is determined by taking the square root of 2500, which is 50 inches. The theoretical ideal placement for a 30x40-inch softbox is 50 inches from the subject! However, there is a less scientific (and easier) way to judge the proper distance from the light to your subject: watch the light as you pull the softbox closer to your subject, and stop when his or her face “pops.”

Diagram and above image—We created a very dramatic glamour headshot of Tishanna by keeping the inside bevel but removing the outside translucent fabric. In this case, we created a fairly large spotlight that was softened a little by the inside bevel. The exposure from the softbox was f11. The hair light was a small StripDome set to f112/10. There was also a spotlight with a 10- degree grid that illuminated Tishanna’s hip when we backed up and shot full length and 3/4 poses. The spotlight was also set for f11. You need to be extremely careful when lights overlap on your subject. In this case, we had to be even more careful because Tishanna put baby oil all over her body and hair to add a shimmer to the reflections from the light and accentuate the “glamour” feel of the image. The shine made it more difficult to control the highlights. The combination of the softbox and spotlight on her hip was f114/10— well within my desired range of 1 stop from the working aperture.

This 3/4 pose shows the effect of the lighting technique just described. In this case, the hair light was set at f112/10. Both images were exposed at f11.

Diagram and above image—The extremely small lights create a harsh lighting effect that can add some snap to an image. Here, we used a couple of spotlights with honeycomb grids to add a stylish look to blue jeans. Two spots were positioned directly behind the camera and aimed at Ruthchelle Melchor’s face and torso. The falloff from the lights places her legs and feet in relative shadow, drawing your eye to her face. The spotlights also create a strong shadow behind her, adding a new graphic dimension to the image. The gray seamless backdrop was also lit with a spotlight without a grid, but covered with a green gel. Honeycomb grids come in varying degrees and narrow the beam of light even further—creating a smaller and even harsher light source!

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*excerpted from the book Softbox Lighting Techniques for Professional Photographers