F Stops and Apertures Explained!!!
Many people are confused about apertures and that little "f' with a number next to it. If you find it confusing, you aren't alone. So don't worry about it. It really isn't very complicated at all, but it takes a little explaining.
The aperture is the opening where the light comes through. More light enters the camera if the aperture is opened wide. Less light enters the camera if the aperture is narrow. Most cameras allow you to adjust the aperture manually by setting the camera in the manual and aperture priority modes. In the aperture priority mode, the photographer controls the aperture while the camera automatically adjusts a compatible shutter speed. In full manual, the photographer controls all the camera functions.
The little "f" with a number next to it tells the photographer how wide open the aperture is. The lower the number, the wider the aperture. It's that simple. The F stop is actually a fraction, and if you think of it as a fraction it will make more sense. Just as 1/2 is a larger number than 1/4, f/2 is a larger number than f/4. So, while f/2.8 indicates a wide aperture setting, f/8.0 would indicate a narrow aperture, since f/2.8 is a larger number. To prevent any confusion, I will refer to F stops such as 2.8 as a "low" number and F stops like 7.1 or 8.0 has a "high" number.
Less light enters the camera when the camera's aperture is narrow. So a slower shutter speed must also be used to achieve an acceptable photograph. But depth of field is also affected. What is depth of field? It simply means both the foreground and background in the photo is visible and clear. A picture with a visible foreground and a blurry background has little depth of field. A photo with both the subject and the scenery behind the subject visible and focused has greater depth of field.
Sometimes in poor lighting conditions things like depth of field may be compromised since a proper exposure is really the photographer's main goal. Fortunately most modern cameras have several tools built into them which help the photographer; things like ISO settings, exposure compensation, multiple on-board light meters and programable flashes.