The amount of light hitting the film is called the exposure. To get a photograph that is not too dark or not too light the photographer uses the f-stops and shutter speeds to control the amount of light hitting the film.
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 (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that primarily determines the ray cone angle and brightness at the image point.
In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself.
The aperture stop of a photographic lens can be adjusted to control the amount of light reaching the film or image sensor. In combination with variation of shutter speed, the aperture size will regulate the film’s or image sensor’s degree of exposure to light. Typically, a fast shutter will require a larger aperture to ensure sufficient light exposure, and a slow shutter will require a smaller aperture to avoid excessive exposure.
In easy words, 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.
This is also known as F value / F numbers of your camera. You need to remember that a large aperture results in a large amount of background blur. This is often needed for portraits or photos with blurry background.
On the other hand, a small aperture results in a small amount of background blur which is typically ideal for landscape or architectural image.
Aperture / F Values list:
f/1.4 Very large
f/22.0 Very small
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. 1/500 of a second will let half as much light in as 1/250.
Shutter speed is the length of time of the camera shutter is open, allowing light to enter onto the sensor. Alternatively, it is the time of your camera spends taking a photo.
ISO / FILM SPEED
Film speed is the measure of a photographic film’s sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras.
Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grain or higher image noise of other types). In short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the quantum efficiency of the film or sensor.
The ASA and DIN film speed standards have been combined into the ISO standards since 1974.
ISO controls the brightness of your photos, and it is a crucial setting to use properly if you want to take the best possible images.
Common ISO Values
ISO 100 (low ISO)
ISO 6400 (high ISO)
Please note, raising your ISO has consequences. A photo taken at too high of an ISO will show a lot of grain, also known as noise, and might not be usable.