Starting out in a new hobby or interest such as photography can be fairly intimating and confusing as all sorts of jargon is strewn about the place. It can take a while to fully understand and learn to apply the many concepts and techniques of photography and no matter how long you have been doing it for, the learning never really ends. The intriguing thing about photography is the marrying of science and art as the path of learning how to understand and manipulate light is embraced. In order to get to most out of light it really does pay to have an understanding of a few of the most basic photography terms. This article is not designed to be a definitive list, but provide explaination some of the simple terms and concepts that contribute to understanding how to achieve a good balanced exposure.
Exposure is all about balancing the amount of light in an image. The idea being that all details are clear, and there is a balance of light and dark tones without loss of detail at either end of the spectrum.
When too much light hits the camera sensor, the image is overexposed. This results in the loss of detail in the brighter parts (or highlights) of the image. In the left hand image the brighter areas are blown out and details, such as texture have been lost from the sand and the white building. Alternatively, if there isn't enough light getting to the camera sensor then the image will be dark and underexposed. This results in a loss of detail in the darker areas (or shadows). In the central photograph the darker tones of the bushes have lost some detail, and the overall effect is a darker image. Balanced exposure preserves all the details in the image from light, to dark and everything in between (mid-tones). To achieve this balanced exposure there are 3 components that can be manipulated to control the amount of light delivered to the camera's sensor. These components are interlinked and if one is changed then at least one or two of the others needs to also be adjusted to compensate. This leads us to the exposure triangle.
At the top of the triangle is the ISO (International Standards Organisation). ISO is a little different to the other two components in that it does not control the amount of light that physically enters the camera through the lens. Instead, the ISO adjusts the sensitivity of the camera sensor. With ISO the higher the number the more light the sensor is able to pick up. In brighter situations a lower number tends to be appropriate, while in lower light or darker situations a higher number may be necessary. A word of caution however, higher ISO's will result in noise. This means that the image will have a grainy quality. The point at which noise starts to creep in to the image will vary depending on the specifications of the camera. Entry level digital single-lens reflex (DSLR) camera's have a smaller sensor (cropped sensor). As a result, they have smaller range of ISO values and tend to show grain at lower ISO's. The reason for this has to do with over excitement of electrons within the sensor and is more technical than this article is going to delve.
As the name suggests shutter speed is the amount of time that the shutter is allowed to remain open when capturing an image. Shutter speed is written as a value of time such as, 1/200sec, 1/20sec or 1sec etc. Being able to control the shutter speed has a number of benefits, namely the ability to take photos in varying levels of light (such as city nightscapes, or full sun situations), and the ability to capture motion either by freezing subjects in motion, or blurring subjects in motion. The considered use of shutter speed opens up a wide range of artistic and storytelling capabilities that can be applied to really enhance travel imagery. The faster the shutter speed the less light is able to reach the camera sensor, conversely the slower the shutter speed the more light reaches the sensor. With slower shutter speeds the use of a tripod or something similar may be necessary to prevent camera shake. This is unwanted blurring that occurs when the camera is not held steady for the time over which the shutter is open. The point at which a tripod is required can vary individually so it's worth playing around to determine how slow to go. A general rule of thumb is to use a tripod if the required shutter speed is greater than the focal length of your lens (for example if using a 200mm lens any shutter speed slower than 1/200 sec will want a tripod).
The final component of exposure is aperture. Aperture controls the amount of light getting to the camera sensor by controlling the size of the opening in the lens. It is written as the letter f and a number , such as, f11. With aperture the smaller the number the larger the size of the opening. Similar to shutter speed it is changed by using controls on the camera but the lens in use also determines the range of apertures that are available. In addition to controlling the amount of light accessible to the camera sensor this function also controls the range of the image that is in focus (depth of field). A low number restricts the focus area to a very shallow band (shallow depth of field), while a higher number increases the band that is in focus to a much wider degree (deep depth of field).
Metering is a determination of the amount of light in a scene. To bring the three components of exposure together cameras have a metering sensor that calculates the amount of light available from a scene. The manner in which the camera meters the scene can be controlled and changed, however this article will not be going into a detailed explanation of this. When using the automatic, and semi-automatic functions the camera will read the light in the scene and will make a determination of some or all of the exposure settings required. When using the camera in the manual setting the exposure values are determined by the user. This higher level of control provides for more options to bring a creative flair to photographic images. While the exposure setting have to be adjusted by the user the camera has a metering display which can be used as a guide to obtain a good exposure. The metering indicator can be viewed either from the screen display or within the viewfinder and the aim is to line up the indicator with the zero point and use that as a starting point to achieve the desired exposure.
Hopefully these explanations of some of the basic photography terms have been useful and easy to understand. Feel free to leave any feedback or comments below. Until next time - happy snapping.