Part 3 - The Objectiv

The objectiv lens constists of a variety of lenses and a holder, to attach the lenses.

Partly there are 15 or more of these lenses in an objectiv, accurately produced, lenses are quite expensive.

There is nothing to be seen of the holder except from the cylindrical shape. In fact inside you will find a complexity of precision mechanics. By changing the flocal length and also by setting the distance of modern zoom objetives it is necessary to adjust group of lenses one to another in high accurary at the same time.

To be able to work with zoom formerly photographers have had lots of objectives with all different kinds of focal length. Today an objective itself offer a zoom with a certain margin of focal length, professional photographers were no longer in need of carrying more than twenty objectives with them, but only two or three.

Part 4 - Focal Length

The focal length is measured in millimeters and can be found on the obcectiv. It tells you, how far the captured section is scaled up or scaled down.

The smaller a focal length is choosen the more can be seen on the picture compared to a longer one. Therefore it is also called wide angle. It is used to take fotos of wide landscapes for example. It is recommanded to use the wide angle only for that purpose, because it happens quite often that pictures look deformated when closeup views are taken by using the wide angle.

The opposite of wide angle is tele. Similar to a binocular tele objectives enlarge the image and show a smaller field of view. The human eye has a focal lengt of about 50 mm.

Objectives not only differ in the focal length, but also in intensity of light, the maximum of aparture opening. An objektiv with a maximum of aparture opening of 2 has a higher intensity of light as the one with a maximum of aparture opening of 2,8. Working with the first one you still can expose in face of bad rates of light.