Sigma 12-24mm f/4 DG HSM Art full frame lens

introduction

unique 12-24mm ultra wide angle full frame AF zoom lens in various mounts (Canon EF, Nikon F (FX) and Sigma mounts)
competes with the Canon EF 11-24mm f/4L lens at twice the price but similar size, weight
announced Sept 2016

12-24mm f/4 full frame lens
Dust and Splash Proof Construction with rear rubber gasket but not as weathersealed as the Canon
Ring-type HSM Ultrasonic Focusing with full time MF
internal focus but zoom extends (unlike the Canon equivalent which has internal zoom)
no filter thread
no rear filter slot (the Canon lens does have one)
close focus 0.24m
9 rounded blades
16 elements in 11 groups - Super Multi-Layer Coating, F-Low Dispersion and aspherical elements, including an 80mm large-diameter molded glass aspherical element
1151g (2.54 lb)
132mm (5.2“) x 102mm (4.0”)
$US1600

dpreview.com's review
- excellent sharpness even wide open but best at 12mm, and even better when stopped down to f/5.6-8
- corners less sharp as you zoom in
- not as sharp as the Canon 11-24mm lens
- well corrected CA and very good vignetting, only 2/3rds EV wide open - both better than the Canon lens
- slight but complex barrel distortion at 12mm, almost disappears by 16mm, slight, complex pincushion at longer focal lengths - less than the Canon lens especially at widest zoom but more complex and more difficult to correct
- measured T-stop for this lens is around T4.6-4.8
Petapixel's review
PhotographyBlog's review
ThePhoblographer's review
SLRlounge's review
LensTip's review
- slight coma in corners and mild astigmatism of 3.4% but better than the Canon lens