Afocal lens is a type of lens attachment that modifies the effective focal length of a camera lens without changing the distance between the lens and the film or sensor plane. Often used in combination with telescopes, spotting scopes, or long telephoto lenses, afocal lenses allow photographers to achieve greater magnification or wide-angle effects while maintaining focus. They are commonly employed in astrophotography, wildlife photography, and specialty applications where precise optical adjustments are needed. Using an afocal lens enables photographers to extend the versatility of their existing lenses and capture detailed or distant subjects without altering the primary lens setup.