Photography is a science as well as an art. A technical person considers three main factors to capture a good picture i.e. Aperture, Shutter Speed and ISO sensitivity but an artistic brain says three factors are subject, subject and subject. My definition of a good picture is an interesting subject reproduced on digital or print media accurately with appropriate details. Understanding of techniques and camera vastly helps to capture images correctly and reduces the number of attempts and errors. Let us consider photography from a technical perspective.
Camera is essentially is light reading device and these three factors determine the exposure of light to the sensors.
- Aperture: - Aperture is the diameter of the lens. The amount of light that sensor receives is directly proportional to the diameter. Higher the aperture size, the sensor receives more light. Aperture is measured as inverse of F-Stop e.g. f/1.4, f/2.8, f/ 4.5, f/11, f/22. Most cameras indicate the denominator (i.e. 1.4, 2.8, 4.5 etc.) in the controls, so it is best to remember - lower the F-Stop value higher the aperture and higher the F-Stop value lower the aperture. Higher aperture (lower F-Stop values) also means shallow depth of field i.e. subject close to the camera is exposed more. To simplify if the subject is close to the camera (e.g. Portrait), consider using lower values of F-Stop (Larger Aperture) and if the subject is far (Landscape) use higher F-Stop (Smaller aperture).
Question Time: For landscape smaller aperture (Higher F-Stop) is recommended but smaller aperture also means sensor receiving lower amount of light. So how does smaller aperture reproduce accurate reproduction of landscape if camera receives lower amount of light?
- Shutter Speed: - Shutter speed represents the duration for which shutter is kept open. Higher the shutter speed, lower the duration for which light reaches the sensor and vice versa. On a sunny bright day higher shutter speed is good while for night photography (without flash), lower shutter speed is required to achieve proper exposure. Shutter speed is measured in terms of time i.e. 1/1000 s, 1/500 s, 1/125 s etc. A steady hand is not good enough at lower shutter speed and hence a tripod is recommended to avoid camera shake.
Question Time: When do we use very high shutter speed but yet pictures can be blurred?
- ISO Sensitivity: - ISO sensitivity represents the sensitivity of sensors (Film in the old days). Higher sensitivity lowers the need for light e.g. ISO1600 requires less light as compare to ISO100. On the flip side, higher ISO means more noise or grain in the picture.
Question Time: What value of ISO, should one use for portraits?
Enough of technical terms and questions; let us look at one picture. What is good about this picture, if any?