These photos were taken to show the different effects of light, but what's actually different?

Question

B&H released an info-graphic today to show the effects of different lighting with modifiers, but they all look the same to me. The first photo looks different with the darker shadows, sure, and there's kind of a color cast on the silver umbrella, but the other three... if they look different I can't tell how. Can someone help me understand how these are different?

http://www.bhphotovideo.com/insights/blogs/photography/infographic-effects-various-light-modifiers-subject.html

Answer 1

Light modifiers are about subtle effects of lights which are very difficult to see on such small thumbnails. Most photography books covering studio photography have the same examples but much bigger.

What changes between these images is the diffusion of light. At the top, there is the least defuse option and at the bottom the most. As diffusion increases, shadows become softer and wrap around the subject more. This results in less contrast and less emphasis of fine textures (read wrinkles and pimples) which is preferable for portraits.

Answer 2

The thumbnails are too small making it hard to see the differences.

When comparing artificial light, we usually look at a few qualities of the light:

• Softness

• Intensity

• Drop off

A soft light evenly lit a subject. A direct flash is hard, creating unpleasant and strong shadows. A soft light is large and it wraps around the subject, making shadow less visible. This is a good light to use for portrait unless you are going for some really dramatic lighting. For a light to be soft, it needs to be as big as possible relative to the subject.

If you have a light that is 8 x 8 feet, if you put your model's face close to it, the face will be lit evenly from all directions, because the light is so huge. This almost eliminates all shadow and is sometimes seen used in cosmetic adverts. If you lit the same face with a flash that is about the size of a biscuit, the model's face will be lit from a single direction, creating awful shadows and highlights.

Secondly, the intensity of the light. Sometimes when the light shines directly on the subject, it creates what we call hot spots. Look at the tip of a model's nose and you will usually see a dot of light, making it looks like her face is oily. When the light is strong and linear, you will be creating a lot of hot spots. This can appear on the model's nose, forehead, cheek bone, lips, chin etc. The face will appear as if it was smudged in oil, unnatural and utterly flat.

This happens when the light is very directional. If you have light that travels in all directions, it is more diffused, and this will reduce hot spots. People use all sorts of techniques to make light travel in a diffused manner. Bouncing off the ceiling, shooting through some fabric, reflecting off an umbrella's inside etc are all good ways to make light travel less linear. This create pleasant lighting for portraits.

Lastly you want the light to be even. You do not want it to reduce in intensity rapidly. This will result in, for example, brightly lit nose and poorly lit cheek. Or when taking group photos, you may end up with a photo where a person face is well lit while the other falls much darker. A large and diffused light source helps.

Generally speaking, a soft light that casts itself across the subject face without hot spots or strong highlights is a good light source for portraits.

However there are also times where you want to use harsh light to make the result more dramatic.

The light modifiers are only there to help control the type of light that the photographer wants.

Answer 3

In the first example, you have a small light source. The result is hard lighting where transitions from highlight to shadow are abrupt. Shadows are dark, highlights are light, and specular highlights are like points (think of the catch light in the eyes).

The others are all various forms of diffuse light. With diffuse light, the shadows get some illumination. This causes the shadows to lighten up, and there are fewer specular highlights in highlight areas. This gives a softer appearance. Additionally, because of the large area of the illumination source, speculars like catch lights are large. For sufficiently large enlargements, the reflection of the light source can be seen in the model's eyes.

Because of my last point, it may be desirable to use an umbrella where the supports are not visible. The shape of the light source will also be visible in the catch light. Do you want an octagonally shaped catch light, or do you prefere a roughly rectangular catch light? I personally find the umbrella shapes in the catch lights on grocery checkout counter magazines distracting. The use of a soft box would be better. But that's just a personal opinion of mine.

Also note the change in illumination power in the various options for the same camera exposure settings to result in an acceptable exposure. There is more light loss when you have to reflect off a surface than if you point the light source directly at the subject. It looks like the difference is up to 3 stops for the different setups shown.

But in terms of differences in look, the main ones are shadow/highlight detail, contrast, and quality of specular highlights. There's a color balance issue as well, on the pictures shown, but, in my opinion, that is an error in the process. Using a proper calibration process, all images should show the same color balance. The reflecting material can alter the color balance, so, unless you know the reflecting material is truly white or silver, the camera/post-processing should be adjusted from one to the other.

Answer 4

You are basically controlling the dynamic range on your subject. The flash alone is almost a spot light, which means the light rays come from the same incident angle. In worst case it is the only light source (talking theory here), which means that the the subject is hit by them some places and all other places are in complete darkness - translating into harsh shadows (too high dynamic range) and highlights where the camera angle and flash angle coincide. The umbrella makes your light source more like diffuse lighting, where light rays come from multiple angles. Where the light could not hit before, it now can. This lifts up the brightness in the shadows and makes the transitions between light and shade wider. The highlight (which is a reflection of the lightsource) is also softer and wider now.

In the examples this is very subtle, but if you look for the light/shade transitions and the brightness of light versus shade, you can note a difference nonetheless. The different ways of diffusing the light affects the PDF (probability density distribution) from the center to the edge.