Tuesday, August 10, 2010

Quality vs. Contrast: Soft Light Ain't All That (Intermediate)



When starting with lighting education, the typical response to unflattering shadows is to seek a softer light source (with less defined shadows). Of course, a soft light source will be more forgiving and many people look better with soft light. However, in my view, soft light by itself is helpful but is not the answer. I suggest instead to emphasize controlling the contrast between highlight and shadow.

To illustrate the difference between these two approaches (quality vs. contrast), check out this test shot:

How does it feel? Except for dramatic purposes, it is not a look that most people seek for portraits. Yet this is a photo with a soft light source. Don't believe me? I agree it sure doesn't look like it is a photo with soft light. However, check out the shadows on the wall. The evidence is right there - shadow edges are blurred - the definition of soft light.

Now, check out the shot above, reproduced here for convenience:



How does it compare to the soft light photo above? It's still edgy (intentionally so) but has a much more mainstream look than the soft light photo above. The shot was done with an SB-800 flash, a popup flash, and of course ambient light.  The flashes were bare.  No umbrella, no softbox, no modifiers, no postprocessing. Check the shadow of the nose or the shadow of the shirt sleeve on the left arm (zoom in if needed). The shadows have a well-defined edge - evidence that hard light was used.

To make the shot work though, I controlled the contrast between highlight and shadow - not letting it get too high. If I recall, I intentionally underexposed the ambient light by about 1 stop. The SB-800 was on TTL, about 1 stop underexposed. My rationale was that with the ambient at 50% of what it should be, and the SB-800 at 50% of what it should be, both would add up to the correct exposure - except that I've controlled the direction of the light. [Note: flash blur is a risk when flash and ambient are equal in intensity but here the shutter speed was 1/250 - therefore any flash blur would not be noticeable.] The popup flash was acting as fill, about 2 stops underexposed if I recall. The purpose was to work with the (underexposed) ambient light to bring up any shadows. If I wanted a less dramatic look I could have increased the intensity of the popup flash instead (e.g., FEC -1.3), which would reduce the highlight-shadow contrast.

The above shots illustrate why in my view, controlling contrast can have more positive impact on your photo than the quality of the light. Fortunately, we don't have to choose one or the other exclusively - we can use both. However, I wanted to make the point that contrast is arguably more important than the quality of the light.

BTW, controlling contrast doesn't necessarily require another flash. For example, we can use reflectors or ambient light as fill.  To learn how to control contrast, please check out the TTL Flash Tutorial (especially Part 2). :)

Related article: simulating soft light with a hard light source.

UPDATE I found a related Strobist.com article (with much better photos!): http://strobist.blogspot.com/2008/10/on-axis-fill-ring-fill-against.html  -- Although David Hobby used a hard and even restricted key light, the photos don't look harsh at all. Instead, they look a bit edgy but pleasant, at least in part due to careful control of the ratios between key, fill and ambient.