Essentials of Photography

A condensed course in the fundamentals of photography.

Today’s cameras are so efficient at taking photographs with automatic exposure and focussing, and program modes, that for many everyday situations the photographer can leave almost everything to the camera and concentrate entirely on the subject matter of the photograph.

However, many photographers will want to know a little of the background to what is happening in their camera. This knowledge will help you to understand some of the terms used in the manufacturers descriptions, and will help if you want to take more control of your photographs and become more creative.

'Photography'
Let’s start with the word itself:

        photo = light, and graphic = picture.

Therefore photography is making a picture with light. The traditional photographer does this by using the effects of light on chemicals, and the digital photographer by the effects of light on an electronic device known as an image chip or sensor. In both cases the light is admitted by a lens and processed in a camera.

The first consideration is to control the amount of light falling upon the sensor. Too much will give overexposure where colours are pale and weak (no colour saturation) and there is no detail. Insufficient light will just give dark, cloudy smudges.

There are two mechanisms for controlling the degree of light input into the camera:

1. Aperture.
If you can get someone to show you a good old-fashioned SLR lens, the operation of the aperture can be seen quite plainly. As the ring which controls the aperture is turned, the aperture opens or closes, allowing in more, or less light.
The aperture is calibrated in f stops, with a high-numbered stop being a small aperture, and a low-number representing a larger aperture.
A typical range on a digital camera lens is f 8to f 2.

f8	f5.6	f4	f2.8	f2

2. Shutter speed.
The shutter is a mechanism which opens and closes rapidly when the photograph is taken. Within the normal range of photography, 1/30th of a second is the slowest acceptable speed for a hand-held photograph, and a good camera will be capable of fast speeds of 1,000th of a second or more.

So why should we have this range of options?

Exposure Value
The answer is that we can make a choice to suit the circumstances and these are the principles on which the choice is made:

The aperture setting is given preference where depth of field is the most important factor. Depth of field is the degree of focus in front of, and behind the main subject. A small aperture, e.g. f 8, will give maximum depth of field so that foreground, middle range and distance can all be in sharp focus.

Conversely a large aperture, e.g. f 2 will give a limited depth of field. We might, for instance, have a nice portrait – pleasant subject, nice lighting etc - but with a messy background. Focusing accurately on the face at a large aperture on the lens will render the face in sharp focus, but the background will be a blur.

The shutter speed is given preference to take movement into account. Any movement in the subject matter requires a fast shutter speed. Also the effects of camera shake can be reduced by using a fast shutter speed.

Exposure Value continued

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