A kit lens is a "starter" lens sold bundled with an interchangeable-lens camera such as an SLR. It is generally a cheap lens priced at the lowest end of the manufacturer's range, so as to not add much to a camera's price. Originally, kit lenses were generally of normal focal length; more recently, kit lenses tend to be cheap zoom lenses that range from medium wide angle to mild telephoto. While prime standard lenses bundled with SLR cameras were generally sharp and fast enough for most kinds of photography, most kit zooms are deliberately limited in abilities, so that the camera purchaser will have an incentive to purchase additional lenses in future.
Cameras and their kit lensesEdit
On film cameras, the first to start offering zooms as the kit lens intead of a 50mm lens, the typical focal length of the kit lens is 28-90mm. With the advent of digital SLR cameras, this has changed to 18-55mm.
The explanation for this lies in the sensor of most consumer digital SLR models. Unlike professional ones, the sensor has been reduced in size with respect to the 35mm film negative, by a factor of about 1.6 times. This means that the image produced by a lens designed for the 35mm system is 'cropped'.
As a result, an 18mm lens placed on a digital SLR produces the same image as a 28mm lens used on a film SLR (or a digital SLR with a full size sensor.)