Abbreviation: EX = "EX Lens" (Sigma)
The abbreviation EX means "EX Lens" and is seen on Sigma products.
Explanation from Sigma
The exterior of this lens is EX-finished to denote the superior build and optical quality, and to enhance its appearance.
See examples of effected products
 | Sigma EX 24-70mm F2.8 DG HSM |
 | Sigma EX 70-200mm F2.8 APO HSM DG OS |
 | Sigma EX 300mm F2.8 APO DG HSM |
See links
| sigmaphoto.com |