Taking good pictures depends mainly on controlling the three basic controls in your camera. They are Aperture, Shutter speed and ISO, as shown in the figure below. Normal digital cameras/point and shoot cameras won’t help you much to get good control over these three parameters, but a digital slr camera would help you to gain a better control.
Aperture is the opening in the camera through which light can enter. Size of the aperture determines the intensity of light entering the film or senor. In other words, greater the aperture more light will enter the camera. Aperture in camera will be shown as f-numbers like f4.0, f5.6, f16, f22 etc. Smaller the f-number, greater will be the opening in the camera. So, if you want a particular object in focus, with background blur then you can select a smaller f-number from your dslr camera. Higher f-numbers are good to bring more objects in the picture to focus, especially when you are shooting a landscape.
For more information on Aperture:
Have a look at this article ,Understanding Aperture
Next parameter is shutter speed. Shutter speed is also a controller of light. We can freeze the action with higher shutter speed. But at higher shutter speed, less amount of light will be entering into the lens and sensor. So, care must be taken to ensure that the image is not under exposed. The difference between shutter and aperture is that aperture will be open always whereas shutter will be opened only for a predetermined time, as set by the photographer.
ISO indicates the sensitivity of the sensor or film in the camera. Higher the ISO value, greater will be the sensitivity of the sensor in the camera. So, you may think that you can set it to the highest available value in the camera. By increasing the ISO level beyond a particular value, you are basically increasing the noise level in the picture. No the question may arise, why the camera manufacturer has provided higher ISO settings. Higher ISO is used mainly during two situations, night photography and action photography. In the case of action photography, you will have to freeze the action, which demands for a higher shutter speed, as a result of which the amount of light entering into the sensor will be less. So you will have to set a higher ISO. In the case of night photography also, you will have to use a higher ISO value, especially when you are using an inbuilt flash or no flash at all.
Above photo shows the manual mode of a Canon EOS 500D dslr camera. “1/30” indicates the shutter speed set on the camera, “F20” indicates the Aperture value and the ISO value of 200 can be seen on the top right corner. Once you understood these three parameters, then you will be able to take really good pictures. Usually, a digital slr camera will have the following modes: automatic, manual, aperture priority and shutter priority modes.
In the case of automatic mode, camera will automatically select the shutter speed, aperture and other settings depending on the scene. But, In the case of manual mode, you will have to set these three parameters. Most of the people will start of with the fully automatic mode, where they don’t have to think about anything, as camera will take care of everything. But this is a bad practice, as you will never learn anything. Aperture priority mode will help you to set your desired f-number and camera will help you to find the matching shutter speed. In the case of shutter priority mode, this is reverse. “Practice
makes a man perfect” so take a picture daily. This will definitely help you to
improve your photography.