Strobist Boot Camp: Lighting 102–Apparent Light Size

Previous assignments here.

This week’s exercise among the Flickr folks doing the Strobist 102 series is Apparent Light Size. The idea here is that the apparent size of the light (not the actual size) is what determines the fall-off of the shadows, or the “softness” of the light. Large apparent light size makes for soft light, where as small apparent size makes hard light. Or large lights make for gentle fall-off of the shadows, and small lights make for rapid fall-off (e.g. sharp edges) of shadows.

The official assignment is to use a fruit, and to vary the distance of the flash (or other light) to the fruit while attempting to keep the angle the same. I chose a rather yellowed acorn squash. Here’s my set up:

The flash is on a light stand with my homemade diffuser directly over the squash. This was the best way I could figure out to make the angle stay the same with each change of the light distance. I made four pictures with the flash 12″, 24″, 48″ and 72″ away from the squash. With each increase in distance I had to double the flash power to compensate, and I tweaked the exposures just a bit in post-processing to try to make the green place mat about the same exposure.

Sure enough, the shadows are very different from one foot to six feet. At one foot the shadow of the stem is barely discernible, whereas at six it is perfectly solid. The body shadow exhibits the same features: soft at one foot, crisp at six.

This wasn’t terribly difficult for me to execute, especially after I’d read some of the comments in the discussion of the assignment. I’m glad I followed the advice to not use a white surface, so that the shadows would be crisp.