Lens

Sometimes it's impossible to get close enough to a subject to fill the frame of your picture. Sometimes you'd like to go further away to get the whole scene. In both cases changing the lens is the most convenient solution.

Normal Lenses

50 mm lenses for 36 mm film are considered as normal, because they see approximately the same field of vision as the human eye. If you buy a camera you mostly get such a lens.

Wide-Angle Lenses

The beanpoles are not parallel anymore on the picture taken with wide-angle lens

Wide-Angle lenses have a focal length less than 35 mm. With 18 mm wide-angle lenses you can record almost 100° of the setting around you. Sometimes straight lines do not appear as such and there will be distortion of close objects.

Telephoto Lenses

Any focal length form 100 mm upward is considered to be telephoto. Most of them are zoom lenses, in which the focal length can be altered. However, these zoom lenses absorb more light and provide a lower picture quality than fixed telephotos.

The two pictures below show the same flower twice: The picture on the left was taken with normal, the one on the right with telephoto lenses.

Normal lens: The background is sharp and looks vivid

Telephoto lens: The background seems very close to the flower and is flat and smooth

Focussing

Focussing is needed to select the part of the picture that should be sharp. When using an autofocus system - apart from the advantage, that you are much faster - you could run into troubles:

1.	Sometimes the autofocus selects the wrong area to focus on. In this case you have to work manually.
2.	Some older autofocus systems do have problems with fast moving targets.
3.	Autofocus systems do not work well with poor light.