First Lesson of Photography - Aperture, Shutter Speed and ISO

                                                          The Exposure Triangle

Photography is all about playing with light, but the term we use is called 'Exposure'. There are 3 ways in a DSLR camera to control exposure.

1.   Aperture – Aperture is the opening for light rays to travel through the lens and fall on the image sensor. In SLR, the size of aperture can be controlled and hence, the amount of light which falls on the image sensor can be changed. When you set your camera at Aperture Priority mode, you (the photographer) selects the aperture and based on the environment light, the camera decides the shutter speed.

2. Shutter speed – The shutter stops the light rays to fall on the image sensor otherwise. When the Shutter release button is pressed, the mirror along with the shutter is raised and light rays fall on the image sensor to form the image. The time for which the shutter is raised can be controlled by controlling the shutter speed and hence, the amount of light which falls on the image sensor can be changed. When you set your camera at Shutter Priority mode, you (the photographer) selects the Shutter speed and based on the environment light, the camera decides the shutter speed.

3. ISO sensitivity - ISO sensitivity is the Sensitivity of the image sensor of a DLSR camera. The image sensor converts the light rays into digital information (the digital photo) and ISO sensitive is the measure of its ability to capture the light. Higher the ISO sensitivity, brighter is the picture and higher the noise (grains) in the photo. Hence ISO should be increased, if the desired exposure is not achieved by combining Aperture and Shutter speed.

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