Comparison of Carl Zeiss 21mm f/2.8 Distagon T* 2.8/21 and Sigma 28mm ƒ/1.8 EX DG Aspherical Macro

Attribute	Carl Zeiss 21mm f/2.8 Distagon T* 2.8/21 ×	Sigma 28mm ƒ/1.8 EX DG Aspherical Macro ×
Diagonal Angle of View (degree)	90.00	75.40
Notes	Available SLR mounts: Canon EF-Mount (ZE), Nikon F-Mount (ZF, ZF.2), Pentax K-Mount (ZK). Nikon ZF.2 version includes CPU interface for autoexposure	Available AF Mounts: Sigma, Canon, Nikon, Minolta, Pentax
Aperture (f)	2.80 - 22.00	1.80 - 22.00
Magnification Ratio (x)	0.2	0.34
Filter Size (mm)	82	77
Type	Wide Prime	Wide Prime
Closest Focus (m)	0.22	0.2
APS Equivalent	1.5x: 31.5mm	1.5x: 42mm; 1.6x: 44.8mm
Lens Construction	16 elements in 13 groups	10 elements in 9 groups, including 2 aspherical elements
Image Circle	35mm	35mm
Focal Length (mm)	21.00	28.00
Brand	Carl-zeiss	Sigma
Name	Carl Zeiss 21mm f/2.8 Distagon T* 2.8/21	Sigma 28mm ƒ/1.8 EX DG Aspherical Macro
Weight (g)	600	500
Diameter (mm)	87	83.6
Length (mm)	109	82.5
Diaphragm Blades	-	9
Focus Details	Manual focus only	Internal with Dual Focus mechanism