lisälinssien

Lisälinssien, often translated as accessory lenses or additional lenses, refers to optical devices that can be attached to existing camera lenses to alter their focal length or perspective. These are distinct from interchangeable lenses, which are designed to be fully replaced on a camera body. Accessory lenses typically screw onto the front of a prime or zoom lens, modifying its optical properties.

Common types of accessory lenses include teleconverters and wide-angle converters. Teleconverters, also known as extenders, increase the effective focal length of a lens, making it appear as if a longer lens is being used. This is achieved by using a system of internal lenses that magnify the image projected by the primary lens. For example, a 2x teleconverter will double the focal length of the attached lens. Wide-angle converters, conversely, decrease the effective focal length, allowing for a wider field of view than the original lens provides. They achieve this by effectively shortening the focal length of the combined optical system.

Accessory lenses offer a more economical way for photographers to expand their creative options without purchasing entirely new lenses. However, they can sometimes come with trade-offs. Image quality might be slightly degraded due to the additional glass elements, and there can be a reduction in the maximum aperture of the lens. The use of accessory lenses is prevalent in various photography genres, including wildlife, sports, and landscape photography, where flexibility in focal length is often advantageous.