Back to my Strobist Lessons then.

Lighting 102: Unit 2.1 - Apparent Light Size

I have always considered a Direct Flash to be a very Hard light source, but I've never really comsidered why. In this unit of Lighting 102, David has explained what it is that defines "Hard" or "Soft" light.

Basically there are 3 "Zones" of light on a subject when examined together will identify whether the light is soft or hard.


1 - The "Diffused Highlight"
2 - The "Shadow"
3 - The "Diffused Highlight to Shadow Transfer Area

The only one of these I didnt find self explanitory was the Diffused Highlight. Basically it's what would be considered the "Well Lit" area of the subject. The other two speak for themselves.

So, the bigger the "Diffused Highlight to Shadow Transfer Area" is, and therefore the more Gradiated the light will appear, the "Softer" the light is said to be. And the flip side of this is of course a very narrow transfer would be hard light.

Hard light will have very difinitive sharp edged Shadows.
Soft light will have very gradual edged Shadows.

Now, what causes this? Well initially I would have thought the Size of the light source, but it's not that simple. Thinking of the Sun for example. It's about as big as a light source is ever likely to get, however it's "Apparent Size" to me is tiny. (Ever pretended to hold the sun between a finger and a Thumb?)

It's the "Apparent" size of the Light Source with respect to the Subject that will determine whether the light is Hard or Soft. (Eureka Moment for me here)

To test this theory David suggested we shoot images of a piece of Fruit, and vary the apparent size of the light source.

Here goes: (Click for full size)





All in all, I think I've had a very successful result from this experiment, and it has definately changed how I think about how a light source (or the apparent size of it) will effect my subjects.

One other point David made on the forums was to keep an eye on the "Specular Highlight" (The reflection of the light source), and how it changed with each setup. Although it's pretty much blown out on my Images, it's clear to see the intensity of it reduces as the apparent light size increases.