See my reviews of Sigma DG HSM Art lenses at 20mm, 24mm, 35mm, 50mm and more.
This aperture series from f/4 through f/11 is an an exceptional demonstration of wild and whacky field curvature and focus shift, yet with outstanding image quality if one is willing to accept and work with these behaviors in the field. Tips for field use follow in the conclusions.
Depth of field tables are useless fantasy for a lens like the Sigma 12-24mm f/4 DG HSM Art. Image quality in practice depends strongly on focus placement in a scene and how that is optimal for the subject matter, which must also take lens behavior into account.
Includes images up to 28 megapixels along with many large crops, all from f/4 through f/11.
Especially at 36MP on up, the photographer must place focus wisely for the subject matter, not just the “1/3 in” rule and not even just the near/far relationships, but also anticipating and compensating for a lens with focus shift and field curvature, which requires special care based on the shooting aperture.