1. Focal length-Focal length determines the lens's angle of view and the size at which your subject appears in the frame.Digital cameras have different focal length because the size of their image sensors vary from one camera to another.
- Normal lenses -are those with a focal length nearly of 35mm,that is somewhere between a wide-angle and a telephoto.This is used in most snapshots people take.
- Wide-angle lenses-They are also called lenses with short focal length.A short focal length has the effect of pushing the subject away from you and making it appear smaller.They have a wider field of vision than the human eye, it can take in more of a topographical expanse.So they can be used for landscape photography.A wide-angle lens can focus on the foreground and background at the same time so they help you take picture where background and foreground both catch the eye’s attention.Some wide-angle lenses cause a problem known as convergence, a distortion that makes vertical structures appear to lean toward the center of the frame. If you plan to do a lot of wide-angle shooting, take test pictures to check for this issue before buying a camera.
- Telephoto lenses-Also called long focal length lenses have a narrow field of view from 105mm-300mm and is better to use them for close-up and portraits.A long focal length seems to bring the subject closer to you and increases the subject's size in the frame reducing the distance between objects in the photograph and the camera’s lens. This allows a telephoto lens to show greater detail than the human eye could see at the same distance.
- Fixed focal length-it means that the point of focus is unchangeable.This kind of lenses are very useful for beginners to learn the basic of photography and they tend to work well for low light conditions.
- Optical zoom-An optical zoom is a true zoom. Its focal length changes and the zoom mechanism itself extends and retracts so an image is magnified by the lens itself. An optical zoom produces the best quality images.
- Digital zoom-is the same that happens when you crop an image with a photo editor software.It enlarges the center of your photo and crops out the edges and all there has as a result the loss in detail and quality of your photo.
4. Macro lenses-Is used to shoot close-ups.Its short focal length allows the photographer to take pictures at close distances without distortions.Today this is included as a camera setting,and they can be used for magnifying the details of already small subjects.
5. Front of Lens Accessories-Single lens reflex SLR cameras have interchangeable lenses but they are very expensive so they are more used by professionals.For the amatours that don't have a SLR a front of lens accessory is a disc that clips onto the front of a camera lens to provide specific effects. While some front of lens accessories filter out light, others mimic the effect of a wide-angle or fisheye lens.This may result in low quality photography.But also many cameras have built-in lenses that cannot be changed.
6. Fisheye Lens-These lenses distort the subject image, producing photos with curved and convex appearances. The fisheye lens was first developed for astronomy photography that seeks to capture as wide a range of sky as possible.Today, the fisheye lens has become popular with landscape photographers, as the lens distortion curves horizons and hints at the earth’s curve.