When you take a picture with your camera set on Auto mode, you are delegating responsibility for determining the correct exposure to the camera. Depending on the 'brain' (or programmed chip) inside your camera, the result may be pleasing or not to your satisfaction. But before you blame the camera for your lousy pictures, it pays to understand a bit what goes on behind the scenes when you press the shutter release button. In this tutorial, we are going to look at what 'correct exposure' means.
A correctly exposed photograph will be one where the optimal amount of light will fall on the focal plane. Exposure on to film will create an image just as it does in for each individual pixel on our digital CCD. Too much light and the highlights will be blown out and the picture will be washed away in white light. Too little light and the image will be dark and less colourful. Correct exposure is a balance between shutter speed, which lets light in over a period of time, and aperture, which is a hole that depending on the size, will allow more or less light to enter the light tight box on our camera.
We know you already know this, if you have come this far with this ebook.
Let's go on and enjoy a more detailed explanation.
Color is a visual property of perception. Camera chip interprets the light that passes through the lens in a similar way as our brain interprets the light passing through our eyes. Our perception of color is a result of the journey undertaken by light.
Light travels from the light source onto an object and then it bounces off the object and continues to travels through our eyes onto receptors. Then information received is processed by the brain. The brain, being very considerate of our psyche, it balances the color of the light to a white point (simulating daylight).
The camera works in a similar manner as the human eye + brain: the light enters the lens and falls onto sensor and then the data gets processed and the software/firmware assigns corresponding values based on camera settings.