Traditional cameras use viewfinders which allow you to set up your shot and, in the case of Single Lens Reflex (SLR) cameras, focus your subject. Viewfinders can also be found on digital cameras, but in addition, almost every digital camera is equipped with a LCD preview screen.
The preview screen can also be used to set up shots, so you may be wondering why both are needed. The simple reason is that the preview screen consumes battery power, so if you want to extend your battery life use the viewfinder instead of the preview screen for composing shots.
Another reason for using the viewfinder is that LCD screens can be difficult to see in bright sunlight. There are many other uses for preview screens, however, and they are essential for most digital photographers.
Preview Screens:
Even if the preview screen is not used for composing shots, it still provides a number of useful functions.
If you are running out of space on your memory card and wish to take a few shots more, previewing saved images allows you to pick out pictures which can be deleted. Some cameras have a thumbnail function which allows you to view many shots at once. This makes it easy to zero in on one particular photograph.
For those who print pictures directly from the camera, the preview screen allows you to select which picture should be printed. Some cameras even have basic editing functions which allow you to crop images and adjust colour and brightness before printing them. These functions can be accessed with the LCD preview screen.
Viewfinde:
If your digital camera has a traditional style viewfinder, it should be used for most of your picture taking. As we mentioned above, using the viewfinder instead of the LCD preview screen will save on battery power. It will also allow you to hold the camera steadier and move the camera smoothly for action shots. Photographers who wear glasses can get a camera with a diopter adjustment -- this adjusts the lens of the viewfinder so that you don't have to wear glasses when shooting pictures.
There are some situations, however, when using the preview screen instead of the viewfinder is recommended.
The viewfinder is slightly offset from the lens. In most situations this is not a problem, but for close-up shots there can be a noticeable difference between what the lens sees and what the viewfinder sees. The preview screen allows you to precisely compose close-up shots because it shows exactly what the lens sees.
Another time it is better to use the preview screen is when shooting objects close to the ground. This saves you from having to get into an awkward position in order to set up the shot.
Through the Lens Viewfinder:
Some of the more expensive digital cameras have a viewfinder which is connected to the lens with a prism. This allows you to see exactly what the lens sees. A variation on this type of viewfinder is the electronic viewfinder (EVF). This is a miniature LCD display which collects light from the lens area. As you are setting up a shot you can also see all of the camera's menus. This lets you change camera settings as you are viewing a scene for immediate feedback. Used in conjunction with a diopter adjustment, this saves the photographer using reading glasses in order to adjust the camera.
