From Longman Dictionary of Contemporary Englishtelephoto lenste‧le‧pho‧to lens /ˌteləfəʊtəʊ ˈlenz $ -foʊtoʊ-/ noun [countable] TCPa long lens that you put on a camera so that you can take clear photographs of things that are a long way away
Examples from the Corpus
telephoto lens• These were made discreetly with the aid of a telephoto lens and with the full co-operation of the club.• Nikon for instance produce a telephoto lens, several wide angle lenses and a fish-eye for their range of models. 