This is not exaggerating when saying exposure is the heart of melbourne photo booth a photograph. When the exposure is set wrongly, an image becomes too bright or too dark. When thing goes extreme, no post process technique can help. No matter how powerful computer is today, the raw file must contain something. That’s why exposure is the first thing a photographer need to learn.
A camera has its exposure limitation
Did you try to take a photo but fail? I don’t mean you capture nothing. What do I mean is that the result image is not usable. Either it is too dark or too bright. If a photo is said to be too bright, it contain dead white pixel which is un-retouch-able. In order words, the image file contains areas which have no detail. It also happen in a highly underexposed photo. However, dead white is more obvious than dead black.
But why an image will contain dead pixel?
A photo will contain dead pixel because of exposure limitation of a camera. Every camera has its exposure limitation. It varies among different models and brands. Exposure limitation is a physical property of cameras. It has been here since day one of photography. Although films have a larger limit than digital, it still has a limit. In digital world, images are presented in RGB (red, green and blue). To make thing simple, let’s dig into black and white first. Let say white have a value of 255 while black is 0. And I made a nice illustration to explain this.
In real world, contrast is often higher than a camera’s exposure limit. While a camera can only capture a maximum of 255, everything falls outside this range will become dead pixel. Changing exposure can be understood as shifting the range that cameras can record. For example, if the subject is very bright, you should step down the exposure. That is letting less light going into camera. In this case, you are shifting the whole exposure range to a brighter area such like the below:
The red rectangles represent the range that a camera can capture. While shifting the rectangle to the right, more detail in white side can be reserved while the dark side have less detail. There are three things that control exposure. They are aperture, shutter speed and ISO sensitivity. And these are the three and the only three elements in the exposure triangle.
Exposure triangle: The basic to create an visible image
For detail of each element, please refer to the individual tutorial. As I have said, the three elements are aperture, shutter speed and ISO sensitivity. All of them are having different duties in the exposure triangle. To make a correct exposure, you need to take a good combination of these three variables. So, the next question will be:
How to make correct combination of aperture, shutter speed and ISO sensitivity?
Well, in the digital world, this is not a difficult job. But you’ll need to make a few thoughts first. Usual approach for me is to make one of the three into auto. Digital cameras have auto metering. This is very accurate given that you know how to use it properly. Therefore, you job is to choose two perimeters which you want to fix and let the camera do the rest. For example, when I take a landscape photo, I usually fix the ISO to 100 and aperture to f8 or f11. Then the camera help me to choose the best shutter speed. Sometime I need to fine tune it by the exposure compensation but most of the time it is correct. In this case, shutter speed is not important to the image because landscape is not moving. No matter it give me 1/500 second or 2 seconds, it won’t affect my image sharpness given that I am using a good tripod. The key points to make a correct exposure photo is to know how do the camera meter and go into semi-auto mode. When you master these two skills, you should have no difficulty to take a picture with correct exposure.