Shutter speed exists because of something known as your camera shutter â which, simply put, is a curtain in front of the camera sensor that stays closed until the camera fires. When the camera fires, the shutter opens and fully exposes the camera sensor to the light that has passed through your lens. After the sensor is done collecting the light, the shutter closes immediately, stopping the light from hitting the sensor. The button that fires the camera is also called âshutterâ or âshutter button,â because it triggers the shutter to open and close.
In photography, shutter speed or exposure time is the length of time when the film or digital sensor inside the camera is exposed to light, also when a camera's shutter is open when taking a photograph. The amount of light that reaches the film or image sensor is proportional to the exposure time
Shutter speed is the length of time your camera shutter is open, exposing light onto the camera sensor. Essentially, itâs how long your camera spends taking a photo. This has a few important effects in how your images will appear.
When you use a long shutter speed, you end up exposing your sensor for a significant period of time. The first big effect of shutter speed is motion blur. If your shutter speed is long, moving subjects in your photo will appear blurred along the direction of motion. This effect is used quite often in advertisements of cars and motorbikes, where a sense of speed and motion is communicated to the viewer by intentionally blurring the moving wheels.
Aperture is a hole within a lens, through which light travels into the camera body. It is an easy concept to understand if you just think about how your eyes work. As you move between bright and dark environments, the iris in your eyes either expands or shrinks, controlling the size of your pupil. In photography, the âpupilâ of your lens is called your aperture. You can shrink or enlarge the size of the aperture to allow more or less light to reach your camera sensor. The image below shows an aperture in a lens.
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An optical system typically has many openings or structures that limit the ray bundles.
Aperture has several effects on your photographs. One of the most important is the brightness, or exposure, of your images. As aperture changes in size, it alters the overall amount of light that reaches your camera sensor â and therefore the brightness of your image. A large aperture (a wide opening) will pass a lot of light, resulting in a brighter photograph. A small aperture does just the opposite, making a photo darker. Take a look at the illustration below to see how it affects exposure.
Shallow Depth of Field (SDF) is the zone of acceptable sharpness within a photo that will appear in focus. In every picture there is a certain area of your image in front of, and behind the subject that will appear in focus.
Aperture refers to the access given to light from the lens to the camera sensors. The size of your aperture (the diameter of the hole through which light enters the camera) controls the amount of light entering your lens. Using the aperture (f-stop) of your lens is the simplest way to control your depth of field as you set up your shot.
Large aperture = Small f-number = Shallow (small) depth of field
Small aperture = Larger f-number = Deeper (larger) depth of field
It may be easier to remember this simple concept: The lower your f-number, the smaller your depth of field. Likewise, the higher your f-number, the larger your depth of field. For example, using a setting of f/2.8 will produce a very shallow depth of field while f/11 will produce a deeper DoF.
When you focus your camera on a subject, your camera will establish a plane of focus â basically an imaginary plane is set and the things on that plane are âin focusâ (more specifically they are at the point of critical focus). I put that in quotes because around the plane of focus (in front and behind) there is still an area of acceptable focus. How long this area of acceptable focus is (or how deep, meaning area from front to back) is your DoF or Depth of Field.
As you increase your aperture number (close down to a smaller opening, or a larger number), say go from f/2.8 to f/4 or from f/4 to f/5.6, the invisible area in front and behind the plane of focus will get larger. Every time you move up in your aperture setting that area of focus in front and behind the PoF (Plane of Focus) get deeper as to include more in that area. So you focus on a person you are setting your critical focus area on them and as you move your aperture setting to larger numbers, you then start to increase how much in front and behind them will also be in focus, you are increasing the depth of what is in focus or in other words the Depth of Field.
ISO in Digital Photography measures the sensitivity of the image sensor. The same principles apply as in film photography â the lower the number the less sensitive your camera is to light and the finer the grain.
ISO is simply a camera setting that will brighten or darken a photo. As you increase your ISO number, your photos will grow progressively brighter. For that reason, ISO is a good tool to help you capture images in dark environments or be more flexible about your aperture and shutter speed settings.
The same principles apply as in film photography â the lower the number the less sensitive your camera is to light and the finer the grain.
Higher numbers mean your sensor becomes more sensitive to light which allows you to use your camera in darker situations. The cost of doing so is more grain (although cameras are improving all the time and today many are able to use high ISO settings and still get very useable images).
An example of a situation you might want to choose a higher ISO would be photographing an indoor sporting event where the light is low and your subject is moving fast. By choosing a higher ISO you can use a faster shutter speed to freeze the movement.
When choosing the ISO setting generally ask the following four questions:
1. Light â Is the subject well lit?
2. Grain â Do I want a grainy shot or one without noise?
3. Tripod â Am I using a tripod?
4. Moving Subject â Is my subject moving or stationary?