A lens acts as an optical system that generates an image of an object. The simplest form of a lens is made up of a collecting lens, which gathers together rays of light and projects them onto an image plane. Modern camera lenses, however, are made up of multiple lenses and mirrors. Some camera lenses… Read more »


The aperture regulates the amount of light that hits the sensor. If the aperture is fully open, a lot of light is allowed through. The more closed the aperture is, the less light is allowed through to hit the sensor. The aperture is mostly a mechanical system that consists of circularly arranged blades which slide… Read more »

Focal Length

The focal length describes the distance between the lens and the focus. A focal length is given in millimetres. The larger the focal length is, the larger the object will appear in the photo at the same distance. It is also an expression of the image magnification at a given distance. The focal length directly… Read more »

Macro Lenses

Using a macro lens makes it possible to achieve a high image ratio. The reproduction ratio describes the relationship between the actual size of an object with the depicted size on the photo sensor. With a ratio of 1:2, for instance, the photographed object is twice as large as it is depicted on the sensor…. Read more »

Telephoto Lenses

“Tele” comes from Greek and has the meaning of “far.” Telephoto lenses enable the photographer to photograph objects “up-close” from a far distance. A telephoto lens essentially functions the same way a telescope does. In comparison with normal lenses, telephoto lenses have a higher focal length. A lens is considered to be a telephoto lens… Read more »

Wide-angle Lenses

All lenses with a focal length less than 50 millimetres are classified as wide-angle lenses. If a lens has a focal length of 20mm or less, it’s classified as an ultra-wide-angle lens. The most extreme form of a wide-angle lens is the fisheye lens. These lenses have a focal length of less than 16mm and… Read more »

Objective Lenses

Objective lenses (from now on referred to as just lenses) are translucent objects that focus light beams through refraction. The first theories of optical magnification by using curved lenses came about a thousand years ago. These theories were further developed in the 12th century. At this time, the reading stone was created, which was placed… Read more »

MF – Manual Focus

Ambitious hobby photographers can’t but help themselves to try their hand at adjusting the sharpness of the photo themselves. Technical utilities can be used to assist in this endeavour. When using a DSLR camera with a live view, a central portion of an image can be enlarged and later perfectly focused after some manual adjustments…. Read more »

AF – Autofocus

Since the 1970’s, there have been attempts to develop cameras with autofocus capability. Besides camera shake, using the wrong focus is a main cause of a photo appearing blurry. Since about 1985, automatic SLR cameras have played an important role in the world of photography. Currently, the speed and precision of the autofocus is so… Read more »