The Sigma 18mm-35mm f1.8 is an incredibly sharp & fast a-psc zoom photography lens. The depth of field is increased because the lens is so sharp. If you are on a Sony a7s full frame camera, this lens will vignette through the first half of the zoom. On Super 35mm, the vignetting is not noticeable.
Sigma 18mm-35mm f1.8 ($29)
From: $29.00