The same source that leaked the lens specs says the new Sigma 16-28mm E and L will be announced on June 1 at 21 Tokyo time.
16-28mm F2.8 DG DN | Contemporary specs
・ Lens configuration: 16 elements in 11 groups
・ Shortest shooting distance: 25cm
・ Maximum shooting magnification: 1: 5.6
・ Number of aperture blades: 9 (circular aperture)
・ Filter diameter: 72mm
・ Size : Φ77.2 x 100.6mm (E mount version is 102.6mm)
・ Weight: 450g
・ Mount: L mount ・ Sony E mount