موازنة الإضاءة .. كتاب فن التصوير الفوتوغرافي

Lighting balance: The need for more accurate cds counters that reduce human error to the maximum extent led to the production of another type of these counters that work as a principle on the telephoto lens and are called spot meters. These counters have a narrow viewing angle that enables the photographer to measure a very small part of the subject. And this angle is so small that you have to look through a special viewfinder embedded in the meter when you want to deal with a subject through it

To understand the importance of a spot meter in taking an accurate reading of a subject, we must first understand what happens when light enters the photocells in the meters.

Different degrees The photocells in the different types of counters mix the light entering them. When the mixing is done, the meter needle moves to stop at a specific reading. It is in fact the average of the different degrees of illumination. This average result gives a moderate gray color in the final image of the print. This method of making photovoltaic cells remains appropriate until you consider working in bright light conditions or poor lighting conditions

Then the meter will err in taking an average reading of the luminance levels, resulting in negatives that are exposed to under or over exposure. An example of this is when you take a reading of a landscape. If you include a large part of the sky, the exposure meter will receive intense lighting, and therefore the average intensity of the lighting will be based on the brightest illuminated part of the scene, which is the lighting coming from the sky. And all other gradations will be less than that, which leads to a negative frontal exposure that is underexposed. As for the sky, it will appear exposed in an excellent way, because the reading was taken according to it. .

The main problem with standard exposure meters lies in their wide angle of view, which causes an exaggerated reading of the sky or an extension of a water surface where the sun's glare is most intense. The conscious choice of the main areas of interest in the scene to take its reading alone will help in solving this problem, but an angle meter A narrower view will be the greatest benefit from this measure, and this is what the spot meter advances. With its narrow viewing angle, it works to measure the average levels of illumination in a small spot and not others, so that it becomes easy to control it, excluding any effect of bright or bad lighting levels.

With the help of the local exposure meter, it is possible to choose the desired tone for a subject to be viewed as a moderate gray and display on this basis. However, selecting the appropriate lighting degree for a subject is not as easy as it seems, as it requires a special skill that arises with the continuous use of counters.

In general, both the positional meter and the standard meter have their uses that do not amount to perfection. It is not necessary to have both types to become a good photographer, and in the end your personal appreciation remains the most important factor in making a successful picture.