Abbreviation: EF-S = "Electro-Focus Small Image Circle" (Canon)

The abbreviation EF-S means "Electro-Focus Small Image Circle" and is seen on Canon products.

Explanation from Canon

EFS lenses are specifically designed for EOS DSLR models with a more compact sized sensor delivering lenses that are lightweight, versatile and supremely portable. With the EFS range, Canons engineers took advantage of the APSC sensor size to produce lenses that are not only lighter and smaller, but also offer photographers far greater wide-angle choice. Owners of EFS mount cameras have access to a complete offering of lightweight lenses extending from 16mm to 400mm (35mm equivalent).

See examples of effected products

Canon EF-S 18-200mm f/3,5-5,6 IS
Canon EF-S 55-250mm f/4-5,6 IS II
Canon EF-S 17-55mm f/2,8 IS USM

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