Soft light is not dim light. The term ‘soft’ refers to the transition from darker areas to lighter areas. In soft light there is no harsh or sharply defined shadow lines – the transition is gentle and gradual. The softest light has the most gentle and undefined shadows making the transition between dark and light.
In the picture above the designer of this festive shop window has been very clever. The two hard point-sources of light are directed each to one of the manikins. On the heads the light is very harsh and hard – you are immediately drawn to the bright light. The hairlines of the manikins are very strongly defined by the hard light. However, your eyes quickly turn from the brightness. As you look down the torsos the two light sources mix and cross-reflections occur between the white surfaces. As a result the light softens and the sharp lines of shadows are lost as you get further down the window. At the bottom of the window the soft light and diffused effect make the presents seem dreamy and romantic. Altogether the scene draws you in and directs you subtly to the presents below. A satisfying and gentle reminder that children’s Christmas presents can be purchased within.
The eye has a natural tendency to be drawn to the brightest light and to the face. The designer has capitalised on this. The eye then naturally moves downward to take in the softer more subtle tones and the more complex scene below. The complexity is softened by the diffused light and gentle hues down there – and yet excited by the reds and strong lines.
How Soft Light is Formed
Hard, sharp shadow-lines are not flattering in many different types of photographs – especially where people are in the shot. Our eyes are naturally tuned to a softened, rounded shape, especially in the human face. So where we encounter hard light our eyes next seek out the softer, easier light to help us interpret shape and form. So for many photographic situations we need to soften light to make it flattering or for the eye to better appreciate the form and shape of the subject we see.
Soft light can be created in many ways. In the natural world it is most often created by diffused light. A cloud layer causes light to lose its parallel beams. Clouds scatter the light in all directions as it tries to pass through the cloud. It is this scattered effect which creates the diffusion. Harsh, hard lines cannot form under scattered light. The light hits an object from many different directions. This causes the lines of definition in the shadows to be spread over the area of scatter, softening them.
Another way soft light forms in nature is by reflected light. When you photograph something that is in shadow, the subject is out of direct sunlight. It is therefore defined solely by light reflected off other things. Reflections from lots of things round about causes a scattering of the light. Again, this induces a softness. So in very bright direct sunlight working in shadow is one easy way to diffuse the light. In some circumstances, photography on a beach for example, the trees and buildings that might create shadows are absent. So in cases like this when you want to soften the light you might need to use a diffuser. A screen of some sort needs to be deployed that will let some light through, but which will create a shadow to soften the harsh, hard sunlight.
In the studio soft light is created by multiple sources of light or from reflectors scattering the light. Of course several strong light sources make a scene look unnatural. So normally one strong point-source of light is used with other weaker lights to fill the darker areas. The use of reflectors can achieve the same end, but creating a scattered light effect from the main light to fill in the light in shadow areas. The aim is to use the secondary lights or reflections to break up any harsh lines created by the main light source. Of course diffusers can also be used to help soften the light. Wide angle diffusers, like beauty dishes, spread the light over a wide area. This increases local reflections and light scatter to create a diffused and flattering light for the face.
Camera flash is a strong point source of light and as such tends to be hard light. To soften the light you can do one of two things. The simplest is to point your flash to a reflecting surface and let the light bounce of that onto your subject. The resulting scatter of light will be very soft once it gets to your subject. Make sure that you do not bounce the flash off a colour that will cause a colour cast in your picture. White is best.
The second way to create soft light from your flash is to put a diffuser onto the flash. There are literally dozens of types of diffusers available for flash units. After considerable experience with different types of diffusers I believe the simplest are the best. Simple push on flash diffusers are best for hot-shoe mounted flash units.
How to Use Soft Light
Soft light is very flattering on the face. Women especially benefit from soft light. The soft graduations and long transition between light and dark irons out lines and softens the angular parts of the face. If you can, create softness with bright lights. It emphasises the eyes and, particularly in young people, lifts the mood of the picture. In the use of soft light look for ways to bring a graduated emphasis to curves with deeper shadows in deeper curves.
The most significant thing to remember about soft light portraiture is that if the light is full on from the front you will tend to make the face look flat. If you bring the light from the side curves will be emphasized. However, if you have one light-source on one side the other side needs to be supported with a reflector. If you don’t the soft light will fall to a darkness and this will make the softness appear sinister rather than flattering. Don’t equally light both sides either. If you use an umbrella on one side to soften light, then use bounced, reflected or softbox light on the other side to off-set it. Also keep the intensity of the secondary light down so it does not overpower your primary light.
As you take a soft light away from your subject it will tend to harden the light. In general a light further away gets harder because the ray lines of the light get to be parallel. This minimizes the scatter effect and so hard shadows appear with well defined light dark borders. Larger sources nearer to the subject tend to be softer.
You can capitalize on this distance effect of light by using a close, dimmer light to improve the softness. Or you can vary the exposure to prevent blowing out with highlights with a close light. A longer exposure will give you a better quality image too if you lower the ISO for less digital noise (and use other settings if necessary). This varied exposure will enable you to soften the light more without creating distracting highlights.