Understanding The Terms of a Digital Camera

Firstly I want to let you know that this is my first entry to the world of blogs. In the first step, here I am going to describe about some of the basic terms used in digital photography. Lets start with the commonly used terms like Shutter speed, Aperture etc.

Shutter Speed:-
As the name indicates, shutter speed is the length of time a shutter is open. Normally it is represented in seconds e.g. 1 sec, 1/250 sec, 1/1600 sec etc.

Shutter speed is one of several methods used to control the amount of light recorded by the camera's digital sensor or film. It is also used to manipulate the visual effects of the final image beyond its luminosity.

Slower shutter speeds are often selected to suggest movement in a still photograph of a moving subject.

Excessively fast shutter speeds can cause a moving subject to appear unnaturally frozen. For instance, a running person may be caught with both feet in the air with all indication of movement lost in the frozen moment.

In most of the digital cameras there will be a mode named as TV (Time Value) or S (Shutter Priority Mode) in which user can select the desired shutter speed for capturing a image. In this mode user can select the shutter speed and the camera will calculate the correct aperture for the exposure (based on the reading of the current metering mode). Shutter speed is displayed on the viewfinder status bar and on the top LCD, turn the main command dial to select different shutter speeds.

Aperture:-
Aperture is referred to the lens diaphragm opening inside a photographic lens. The size of the diaphragm opening in a camera lens regulates amount of light passes through onto the film inside the camera the moment when the shutter curtain in camera opens during an exposure process. The main function of a camera lens is to collect light. The aperture of a lens is the diameter of the lens opening and is usually controlled by an iris.The larger the diameter of the aperture, the more light reaches the film / image sensor.

Aperture is expressed as F-stop, e.g. F2.8 or f/2.8. The smaller the F-stop number (or f/value), the larger the lens opening (aperture). Don't be confused between the words 'Aperture value' and 'f/value'. Aperture value" is simply another way of saying f/value.
The below picture shows the different aperture values and the hole of iris.

Opening the aperture (reduce the aperture value):- Objects closer and farther than the focused subject will be more out of focus. For instance if you take a picture of a flower against a landscape with the aperture open, the landscape in front and behind the flower will be blurred, emphasizing only the flower.

Closing the aperture (increase the aperture value):- The range in focus expands forward and backward. For instance, if you take a picture of a flower against a landscape with the aperture narrowed, the landscape in front and the behind the flower will be in focus.

Exposure and Metering:-
Exposure Compensation is a feature of a camera that allows you to adjust the exposure measured by its light meter. Usually, the range of adjustment goes from +2 to -2 EV in 1/3 steps. Correct exposure is essential to successful photography, and an understanding of exposure and light metering is a core skill for anyone wishing to explore the art of photography.

E.g. Exposure Compensation +/- 2 EV in 1/3 EV steps :- This means that you can adjust the exposure measured by the light meter by telling the camera to allow more light in (positive exposure compensation) or to allow less light in (negative exposure compensation).

Exposure is set by adjusting two settings; aperture and shutter speed. Between them they control the amount of light that hits the sensor (or film) when the shot is taken.

Let’s take an example. You set your camera to automatic, point it at a scene and take a light reading. For the sake of argument, say your camera’s lightmeter sets an aperture of f8 and 1/200th of a second. You can produce the same exposure by increasing the aperture by one stop to f5.6 and halving the shutter speed to 1/400th of a second, because this lets the same amount of light through to the sensor. Similarly, reducing the aperture to f11 and setting the shutter speed to 1/100th of a second will also produce the same exposure.

However if you alter one setting without altering the other you will change the exposure. In the above example, changing the aperture to f5.6 but leaving the shutter speed at 1/200th of a second will increase the exposure by one stop, or one EV, making the picture brighter. Decreasing the aperture to f11 will reduce the exposure by one EV, making the picture darker.