All about Composition and your Camera
Mass dominates over smallness, sharpness over blur and light over shade.
Light is the source and life blood of photography. It is the material which we are supposed to shape with our tool, the camera, and is a material superior to that tool. The effect of light will outdo any other effect the camera is able to produce. It will be stronger than any pictorial distinction which size or definition can create.
Even a comparatively small area of light will attract more attention and convey more emphasis than all the rest of the picture which is darker. Some blurred and even empty patch of light will draw our eye more strongly than all the shadows, however well defined and full of meaning they may be.
Light's emphatic power is so limitless and acts so automatically that it can be the photographer's pitfall. More than any other means at his/her disposal, light will tempt you to superficial exaggerations and confusing elaborateness. All the initial effort put into selecting the right subject, the right distance, the right view, may only too easily be scarified again by yielding to the temptation of playing around with light
Masterpieces of photography do not necessarily originate from studios with the most imposing lighting equipment. Even light cannot give emphasis amidst an orgy of lightness.
And this goes for all the methods of photographic emphasis : they live on contrast. Anything said just before may be found equally true turned the other way round in some cases. If the image is full of large masses, the sudden smallness of a detail may command attention. If the image is sharp all over, some spot of intentional blur may win importance. If the image is bathed in light, the only point of shadow may catch the first glance. Values are relative.