How a Flat Reflector Makes for Great Lighting
A light reflector is used to modify the lighting effect so that it is softer and falls more evenly over the subject. With the reflector, the harsh light is diffused and drastic shadows and contrasts can be avoided.
Surface of the Reflector
The surface of the reflector plays a major role in the quality of light which gets reflected, and a flat smooth surface is regarded to be the best for optimal results. So, a flat reflector will give a much smoother and even light.
Comparing the Light Reflector to Surfaces
To show that the flat reflector is the best for lighting, you need to compare it with other surfaces. In order to bring out the effect more prominently, choose a subject which has a shiny surface like a metal box.
Place the metal box on a white surface and set up the light reflector on the side so that the light falls on the front panel of the metal box. When you use a reflector with a twisted surface, you will find certain area dark on the box and some are more brightly lit. The shadows are basically due to the effect of areas of the twisted surface throwing the light away from the box.
Now, use a light reflector with a curved surface. You will find the reflection a little more even than the first, but still you will find quite a few areas which are dark and light on the metal box.
Only when you use a flat light reflector you will find the lighting effect totally smooth and even on the metal box. This is because the flat reflector is able to reflect light uniformly throughout its surface area, which gives the light an even spread.