We can control the Exposure with these three elements .
1-ISO 2- Aperture 3- SHUTTER SPEED
ISO – Measure the sensitivity of digital camera to the light . So what does sensitivity mean? low sensitivity means that the sensor has to be exposed to light for a longer period of time than a sensor with a high sensitivity in order to properly expose the image. it is always a better idea to go with low sensitivity or low number of ISO. as you crank up the ISO level the chances are more that you are introducing noise to your image .
Aperture – The size of the opening in the ires of the lens. Aperture is the hole within a lens the more you open the hole the more light travels into the camera body, it is easier to understand the concept if you think about our eyes. our eyes works same. The pupil is refer to as aperture in photography. The amount of light that enters the retina which works just like the camera sensor
Note: When we change the aperture we change the dept of field as well it is better to keep that in mind.Aperture is measured using F-stops
the size of circles defines the size of the lens aperture the larger the f-number, the smaller the aperture.
SHUTTERSPEED – is the amount of time that the shutters of the window are open. The longer you leave them open the more light comes in.and shutter speed also controls the amount of blur in image for example . with longer shutter speed you always need tripod or monopod to prevent from shake otherwise the image become shaky or blurred .