For all photographers who use a DSLR camera, at least one lens is required to accompany a DSLR body to take a photograph. Unlike a compact point and shoot camera, in which the camera incorporates the lens into the body, making the lens and body one item and therefore not having the ability to amend the lens in anyway, SLR cameras are sold in two parts.
Firstly, the body, which is the considered the primary part of the camera, as this is what processes the photograph and secondly the lens, which, for those who are not photographically savvy, is the long, cylindrical part which protrudes from the front of the camera body and arranges the light that enters in to actually create different image perspectives.
Prior to any photograph being taken, the photographer must first attach a lens to their DSLR camera body. For the majority of general consumer DSLR cameras (i.e., those aimed at the widest possible market, from amateur photographers to semi-professional), most will be sold with at least one lens, known as a kit lens. Suitable for taking general photographs, they are not designed to be particularly efficient at taking photographs that require a certain perspective and using a camera with this lens is often seen as the next step up.
However, unlike on a compact point and shoot camera, which has a fixed lens, this lens can be removed and replaced with a different one, such as one with a greater focal length or wider aperture, so to be able to produce a varying style of image, offering a different style of image.
Due to the vast amount of lenses that are available, deciding on the one that is the most suitable for you as an individual photographer is far from being an easy process. Prior to any lenses being looked at or considered, it is important that several questions are answered and points are considered, including the actual type of DSLR camera that is being used, what type of photography is carried or planning to be carried out and any additional needs or circumstances that should be taken into consideration.
Whilst searching for a new lens will be possible without taking note of this information, the process will be one that is much less time consuming and complex if it is all taken into consideration. However, as this information can be particularly laborious to digest and become fully aware of it, it can be difficult for an amateur photographer to take it all in. Therefore, as the needs of an amateur photographer will very often be substantially less than professional photographers, the basics of the information would more often than not suffice when choosing a DSLR camera lens for an amateur photographer.
The reason why it is important to know what type of DSLR camera is being used is that lenses are camera (sometimes model but at least brand) specific, meaning that they cannot be interchanged between cameras from different manufacturers.