More about surfaces vs modifiers

More about surfaces vs modifiers

Jul 05, 2021

I’m usually writing about diffusion confusion because of the rhyme. I haven’t come up with a clever term for another area of confusion when it comes to photographic lighting. That is understanding reflections. A common misconception is that reflections are determined by the light source. But it is the surface of the subject that has the most effect on the appearance of reflection

Let’s Look at the Photos

People talk about silver vs white saying that silver reflectors are more specular. I disagree. silver reflectors may be more efficient (brighter) and more directional (increasing contrast). But highlights will be the same—determined by the subject’s surface.

I’ve set up this scene with a variety of surfaces including a matte surface goblet, a shiny can, a mirror, a mannequin, a wine bottle, a tennis ball, and an index card. I then lit it with a silver deep zoom reflector, the same reflector with diffusion, a 7-inch silver dish, the same with diffusion, a softbox, a shoot-through umbrella, a white reflective umbrella, a textured surface silver lamé umbrella, a shiny silver umbrella, a diffused umbrella, and a spotlight.

The exposure varies with the efficiency of the modifier and the shadows edges vary with the size of the modifier. Then there are the highlights. Notice that they are similar across all the modifiers, with only the size changing from one modifier to the next. On the matte surfaces like the goblet, the mannequin, and the tennis ball there are no differences between the silver deep zoom reflector, the softbox, the white umbrella , or the silver umbrella except for the exposure, for which I adjusted the power of the strobe to maintain exposure between these photographs. On the shiny surfaces like the can and the bottle the specular, mirror-like, reflections differ mostly in size and shape.

The shiny silver modifiers versus the white modifiers make no difference on matte surfaces, such as skin or tennis ball. And going back to diffusion, as you can see from the deep zoom and the 7-inch dish reflectors with and without diffusion, diffusion spreads the light, but doesn’t change the shadow edge (not softer), and lowers the power of the light (which you cannot see here as I adjusted the power of the light to compensate for each modifier).

View fullsizeCan you tell which modifier was used to light each of these images?

Can you tell which modifier was used to light each of these images?

What I want you to see is that changing the light source doesn’t change the specularity of the subject. The subject itself determines the specularity.The different modifiers change the power of the light, the spread of the light, and the color of the light. The matte surfaces reflect the light in all directions and the surface looks the same from any viewing angle. Shiny surfaces are like mirrors and reflect more directionally and look different depending on where you are viewing from. The tennis ball is always rough and matte. The wine bottle is always shiny. Changing the light source doesn’t change the shine of the glass, though different sources will look different as these are direct reflections of the light source. It is all about how the subject presents the light back to the camera. Changing the bottle, such as by sand-blasting it to a matte surface, will change the surface, which will then look the same no matter the light source or where it is viewed from.

Here is another set, using an 8 ball, a clown nose, and a cue ball. Three lighting setups: small shiny 6 inch metal dish, 30 inch shiny silver umbrella, and the same umbrella with a diffusion panel. The shiny black 8 ball shows differences between the light sources. The cue ball has small clues about the light, but the clown nose is the same under each of the different lights.

Here is one more set with myself in the mix to see the light on human skin. The modifiers used: Bare Bulb (no modifier), shiny silver umbrella, white reflective umbrella, diffused umbrella, pebbled silver lamé umbrella, and a white shoot-through umbrella. Again the differences are the shadows/contrast and the specular highlights (the wine bottle and the catch lights in the eyes). The tennis ball and my skin are basically the same in all the images.

So, why the different modifier surfaces? For efficiency (power), shape and size (distribution of the shadows), spread (contrast), and color. Shiny modifiers put out more light on the subject and the concentrated light is less diffused, meaning it spreads out less, which keeps the light from bouncing off the environment making shadows darker (higher contrast). Less shiny modifiers put out light in a wider angle with fewer photons striking the subject, so less intensity. And those photons bypassing the subject will bounce off the environmental surfaces opening up the shadows (lower contrast).

About the four images above—they are all lit by umbrellas. A = shiny silver umbrella, B = reflective white umbrella, C = diffused umbrella, D = shoot-through umbrella. How well did you do?

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