Best wide angle lens for the sony a7s?

Here is what the site says about that.

From Sony a7S: Sony a7S: A mirrorless camera by Sony with a 12.2-megapixel full frame sensor, announced in 2014. Specs - Maker: Sony - Mount: Sony E - Sensor: Full frame, 36 x 24mm, crop factor 1.0 - Resolution: 12.2 megapixels - Stabilisation: none in the body; use stabilised lenses for slow shutter speeds - Announced: 2014 - Type: mirrorless camera Focal lengths on it Full frame is the reference size: lenses frame as marked. ...

From Laowa 15mm f/4 Wide Angle Macro: Laowa 15mm f/4 Wide Angle Macro: A macro lens by Laowa for Full frame cameras, 15mm f/4. An ultra-wide that focuses to 1:1.

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