Want this question answered?
The shutter.
the ISO setting in your camera controls the shutter speed therefore increasing or reducing the amount of light captured by the film/photocell
The thing that gathers light through a lens and projects an image on a film is... its really rather simple. Its a camera. How easy was that! So to explain the process, A camera gathers and bends light with a lense, this lense then projects an image onto a light-sensitive film to record a scene. When you take a picture with a camera, a shutter opens to allow light to enter the camera for a specific length of time.
It controls the amount of light that reaches the film.
This part is called a Lens, on the camera and the glasses the are made of either optical glass or optical plastic, in the eye the lens in an organic material. Lens allow light to enter the camera, eye or glasses, and focuses that light on a surface such as the camera's film, the eye's retina, and the glasses wearer's eyes.
Exposure is the combination of aperture and shutter speed. Aperture (measured in f-stops) determines the amount of light that will enter your camera. Shutter speed (measured in seconds) determines the amount of time that the shutter will stay open to allow light to enter.
Answer 1A very brief and very over-simplified description is that a camera is: 1. a "box"2. with a light sensitive media [film or electronic light sensing grid] at the back side,3. with an opening [lens or pin hole] at the front to admit light from a subject and to form an image on the media,4. and a method [a diaphragm to control the intensity of the light, and a shutter to control the length of time the light is allow to strike the media] of controlling the amount of light getting to the media.
The highest shutter speed available to you will give you the darkest exposure, while the lowest shutter speed available will give you the brightest exposure
a device to reulate the amount of light entering the lens of a camera
SHUTTER in Camera controls the amount and time of light that the Sensor will exposed to.
The functional opening is the aperture, the opening that controls the amount of light that hits the photosensitive surface. You may have a camera with interchangeable lenses that screw into and out of the camera's body. The opening into which the lens is screwed is not the aperture.
The largest camera aperture is f stop 1.4, which lets the most amount of light into the camera.