softness of light

Started Jun 2, 2008 | Discussions thread
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John down under Veteran Member • Posts: 8,238
softness of light

I've been discussing lighting and lighting modifiers with Joe Demb and it became apparent that we both assumed we were talking the same things based on certain words when in fact we were actually talking about different ideas. Needless to say, our discussions became more useful once we'd figured that out.

It appeared to me that there may be lots of people who have different ideas about what certain lighting concepts mean. I decided that it might be useful to provide some kind of overview about what's meant by soft light.

Some people may think softer light means dimmer light, but that's not the standard meaning when it comes to lighting. The softness (or hardness) of light is about the degree to which the light wraps around a subject to provide even illumination with soft-edged shadows.

Soft light can only be achieved by using a large enough light source as seen by the subject, with the light being diffused enough to travel in lots of directions from the source rather than being funnelled from each part of the light source in a given direction (as you might get from using a grid over a light source).

From a given distance, a (suitably diffused) larger light source will mean that light from that source illuminates each part of the subject from more directions at once to create softer light than can be provided by a smaller light source. The larger light source effectively fills in shadows better than harder light from smaller sources by hitting from more directions at once. The classic example is comparing bare flash with its tiny are of originating illumination to that same flashgun firing into a softbox, which provides a large area of well diffused light to directly illuminate the subject. Bare flash looks more like the harsh and unflattering deer in the headlights look, whereas the softbox provides more natural looking direct illumination of the subject.

Sunlight generally represents a very large light source as seen by the subject. Direct sun isn't quite as large as indirect/more diffused sunlight. We tend to base how natural lighting looks by comparing it to how direct of indirect sunlight would look when illuminating the subject. Using the indirect sunlight light coming through a window or door can often provide suitable soft lighting for portraits. Of course, the balance of lighting intensities and directions also contributes to natural and/or pleasing looking lighting.

Smaller diffusers are far less effective at creating soft light through direct illumination of the subject than are larger diffusers (without considering how efficient the diffusers are at projecting light towards the subject without losing too much intensity - too many f-stops worth of light).

On-flashgun diffusers are relatively small compared to larger diffusers like umbrellas and larger softboxes. However, when it comes to lighting modifiers that can be used on a flashgun on a camera or camera bracket, larger diffusers will still provide softer direct lighting of the subject than will smaller diffusers. Size does matter.

Bouncing light from the flashgun off a suitable surface (like a ceiling or wall) produces even softer lighting of the subject as the external bounce surface acts like an enormous diffuser, as seen by the subject. When bounced light is used in combination with direct illumination - via suitably diffused direct illumination from the flashgun/modifier - more natural and pleasing results can be often be obtained than when using either bounced light or direct illumination on their own.

There are no absolutes here about what's right and wrong in terms of what lighting should be used, just general observations about what does what and how well people often perceive the results to work for them. Sometimes soft lighting is preferred and sometimes harsh lighting might be preferred (eg as a kicker from the side). However, what makes light soft and hard isn't rocket science.

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Cheers from John from Adelaide, South Australia
John Harvey Photography
Canon 40D, Fuji F100fd

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