I'm rather one eyed about Sigma's 50mm ART lens.
This shot at f/2.8 shows just how circular that aperture stays as it stops down which directly translates to beautiful out-of-focus background textures.
This one's definitely a keeper. As for the subject material ...
Photo: Robert Rath, 'One Eyed', 1/60s f/2.8 ISO320 50mm