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Flash – Controlling the Direction of Light

by David L. Tong

If you’re new to flash, please read my previous flash-related articles here, here, and here, before proceeding to simplify your learning process.

Image Courtesy of Amazon.com

Image Courtesy of Amazon.com

Before we begin, this article will only benefit users of external flash guns that will allow you to tilt, swivel, and rotate your flash head such as a Canon 580EX II (illustrated), or practitioners of off-cam flash triggers.

A dedicated flash unit emits more light than a standard built-in flash, enabling you to light up wider and farther distances as well. In addition, most higher-end models allow you to change the angle of the flash head, allowing you to control where the light will travel and reflect from.

This, I believe, is one of the most important selling points of an external flash gun.

While the ability to throw more light to a subject is great, using a dedicated flash for direct lighting only is, in my opinion, under-utilizing an advance piece of equipment.

An external flash will have some disadvantages such as size, the need to carry another piece of equipment, the need to carry more batteries, etc. The advantages, however, outweigh the negatives, especially if you shoot indoors. The ability of external flash to provide more light, directional light, faster auto-focus assistance, strobe effects, and saving your camera’s battery consumption are much more important features you gain than the mere size/weight issue, if you’re always concerned about creating your own light.

As I’ve mentioned in my previous article, Get A Flash First, a lot of ideas and opportunity open up if there’s enough light for your photographs. I strongly suggest you obtain one and see what you can do with a dedicated flash.

In this article, we’ll concentrate on how to tame light by controlling its output and direction.

Most users use their flash just like a built-in flash. Firing the light straight towards the subject. The result will usually disappoint as the light pattern is too narrow and bright in relation to the whole scene. The resulting photograph will look exactly like a built-in flash as well, with human subjects having bright forehead, nose tip, while lacking any separation from the background and casting a sharp, hard shadow behind the subject. While you can control your flash output and ambient exposure to make the image look better (as mentioned in the other article), the overall result is far from ideal. The solution is to direct the angle of your flash to create a more flattering broad light that’s not coming from the same angle as the camera.

Before I continue, the suggestions I’ll make are merely general tips, as with any aspect of photography, you are free to bend or break any rules or suggestions based on your pre-determined vision on your photographs). There are a lot of useful creative ways to utilize direct flash or hard lighting, but that’s not the scope of this article. In addition, we’re applying the techniques mainly on human subject and portraiture.

In addition to the discussion, I’ll be using the sun as a common reference as a lot of intermediate photographers tend to understand the sun better than a light source that they can control, not realizing that the principles of light is the same no matter what the light source may be.

Law of Reflection

Law of Reflectance

Angle of Incidence (angle where the light is coming from) = Angle of Reflectance (angle where the light will be reflected to)

That means that the angle where the light is coming from will be the same as the angle it’ll be reflected when bounced. If you’re lighting came from a 45-degree angle, the light reflected will be heading towards 135-degree angle. If you’re light is coming in at 90-degrees, then it’ll bounce straight back at 90-degrees towards the source. If the light is coming from 20-degrees, then it’ll bounce off at 160-degrees, and so forth. Light cannot bend on its own, so just imagine you’re banking a shot off the cushion if you’re playing pool, unless you spun the ball, the angle of the ball’s rebound when it hits the cushion will be the same angle as the ball’s approach towards the cushion.

Common Usage #1: Direct Firing.

Direct Flash

Direct Flash

Most people will mount their flash unit and starts firing directly towards the subject. The flash’s metering system will calculate the right amount of light used for proper exposure, much like how the camera’s automatic metering works. The benefits of flash are still there such as freezing the subject and having ample light for a good exposure. The problem with such a technique would be the fact that the distance and area where the light travels will diminish abruptly resulting dark backgrounds in most cases.

In addition, the subject will often have very harsh lighting that’ll make most human faces appear flat and greasy due to hotspots reflecting the light from the flash. The odds of getting red-eye effect is also increased.

The problem started with the flash itself. The 3-inch long surface of a flash is very narrow, it’s similar to a pin-light. To use the sun example, imagine if you’re lying down on the floor and you’re looking straight at the sun at high noon with no clouds. You’ll notice that your shadow behind you will be very defined and your face will bounce the light all over the place (well, assuming you have a camera to photograph yourself lying on the ground, that is). There will be little to no shadow cast on your face and every aspect of your face will be lit pretty evenly, in short, flat lighting.

I need to point out that direct flash is important in certain situations as well, mainly to lift shadows from the shaded areas of the subject. For example, if you’re shooting outdoors and the sun is casting deep shadows under your subject’s eye, or if your subject is wearing a brimmed hat, a touch of fill flash is a must if a reflector isn’t present to bounce the light back from underneath.

Also, if there’s absolutely no nearby wall to bounce, using a small bounce card can effectively and subtly lift the exposure without being over-powering in the image. In short, direct flash should be used as fill or supplementary light, not the main light.

Common Usage #2: Adding a Diffuser or Light Modifier.

Using a diffuser is actually less common than the next item on our list, but I want to discuss this technique first as most people uses direct flash techniques with using diffusers.

Direct Flash with Diffusing Material

There are many diffusing products available these days, all claiming to produce softer light than the original light pattern from the flash gun. Most products are primarily using some form of opaque plastic material to scatter the light instead of having a patterned light beam emitting from the flash head. Some of the popular ones include the Sto-Fen Omni-bounce, the various Gary Fong diffusers, the Spectra bounce card and diffusing kit, etc. While they all work as advertised, there are some misconceptions on what they can and can’t do.

The products make your light source softer, but it doesn’t necessarily make your light source LARGER. The casual description of what a direct flash is as long as your subject see the light in front of them, then it’s direct frontal flash. The products merely give you a more scattered light, but it’s still originating from the camera’s position and scatters the light around the radius of the flash. In essence, the angle where the flash head is pointed at doesn’t matter as much since the attachments try to function like a bare-bulb flash of yesteryears.

They are useful to soften light, but will not create directional shadows on your subjects to create depth by itself. Such products merely scatter light all over the place, as a result, your images merely look like a cloudy, overcast outdoor photo where the shadows are light and flat.

Such products also reduce your flash’s efficiency by quite a bit as the diffuser is placed really close to the flash head and bulk of the light is altered before it had a chance to naturally spread. This makes the zoom function of your flash relatively useless as well. These products will definitely help your output, but is less flexible and glamorous than what the manufacturers claim to be.

Common Usage #3: Bouncing Off Ceiling Vertically or 45-degrees.

Once you get an external flash, most people will think that the “advanced” way to use it is to angle the flash head 90-degrees vertically, pointing the camera towards the ceiling hoping to bounce the flash onto the ceiling and the light will scatter towards their subjects. Some will angle their flash at 45-degrees forward and upwards to do the same thing.

The idea is sound, but many don’t realize why they’re doing it in the first place. The whole idea of bouncing is to soften light. The only way to soften the light is to make it appear that it’s coming from a much larger surface than your 3-inch-wide flash head. By bouncing a concentrated beam of light towards a larger surface like the ceiling, you’ve essentially turned your 3-inch light source to a much larger light source before it reaches your subject. How much larger you ask? Try aiming your flash from a standing position towards a ceiling, you’ll see that when the light hits the ceiling, your small light becomes a larger soft light about 3ft in diameter. That’s an over 10x larger light source origin before it reaches your subject!

The result is a more flattering soft light that will take care of the sharp shadows and glaring hot spots on your subject’s face. It will definitely be an improved image!

However, this is, again, a limited way of using the flash. Remember the light rule of incidence and reflectance and how it applies to the sun. If you’re bouncing the flash towards the ceiling, the light is now coming from the ceiling. In short, from above the subject. What does that remind you of when it comes to shooting outdoors? That’s right, high-noon sun!

When shooting outdoors, you’ll notice that high-noon sun is positioned around 10 to 2-o-clock position of the subject. That kind of lighting casts shadows underneath your subject’s forehead, nasolabial folds (the crease from your nose to lip edge along the cheeks when you smile), brow, nose, lips, chin, etc. The result would be the all-too-common raccoon eyes and deep brow look that are unflattering as well. This problem is multiplied on subjects with sharper facial features such as Caucasians and Indians. The sharper their features, the deeper the shadows created.

Bouncing is a good start, but we need to use it more carefully to make our subjects look good.

A Better Way to Use Flash: Angle Bouncing

Light bounced off white wall to the left.

Light bounced off white wall to the left.

So if we don’t bounce off the ceiling, where will we bounce? Anywhere!

Anywhere from an angle, that is.

As mentioned earlier, it’s more flattering if you can create your light from different angles to give your subjects some depth and definition. The way to do that is to bounce your light off a surface to the left or right of your subject. You can even direct your lighting so that the light either comes directly towards your subject or from behind, as long as it’s not on the same axis as the lens.

The photo of my son, Marcus, having breakfast is an example of a simple light coming off the left wall. The wall is merely 3ft away from the subject and the flash had no diffusers or modifiers. Majority of the light came from the left and a touch of spillover light from the flash head itself went forward. Notice how the shadows are “longer” near the right side of the frame compared to the left. In addition, notice that there aren’t any hotspots reflected off the glass in the foreground that’s merely inches away from the flash itself?

The examples below are from a recent wedding that I shot. The bride’s portrait was lit from the left wall, the wall was about 10ft from the subject resulting to a much larger light and softer light source. Note how the texture of her dress and her necklace was brought out due to the soft lighting. A harder light or direct flash will render those surfaces flat and lifeless. Take a good look at what angle the light was coming from as well, it’s subtle, but the light wasn’t fired directly to the side of the bride, but a little higher than her head causing some spill-over light to create a soft Rembrandt light on her face.

Bounced Upper Left of Camera

In the photo to the below shows how you can create a soft frontal lighting with a touch of directional lighting indoors. A large, 15ft, white projection screen was behind me when I took this shot. The screen was approximately 4ft higher than my seated position and the couple were across the dining table about 6ft in front of me. I bounced the flash off my right shoulder onto the large screen and the white screen acted as a huge softbox for me.

Bounced Behind the camera

As you can see, the source of the light is quite frontal, but the shadows that the angled flash cause were quite apparent. The man’s forehead tells the location of the light source, which is upper-right. Despite the dim lighting and the close proximity of the subjects to the light source, you can still achieve incredibly soft lighting with nothing more than an on-cam external flash.

How does bouncing off walls correlate with sunlight? If you bounce off a large and far enough surface, you’ll mimic soft lighting coming from a north-facing window! Low angles will also mimic the pleasing light path of sunrise/sunset scenes. If you’re wondering why sunrise/sunset lighting are so pleasing for portraits, it’s because of the angle the light is coming from and how diffused the sun’s light rays are during those hours.

There you have it. Develop your brain to see where you can direct your flash gun to get a light source other than frontal or ceiling bounce to create more pleasing photographs!

04/29/09 Update: Part II of Controlling the Direction of Light is now available!

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