Comparison of Olympus 12-40mm ƒ/2.8 Pro M.Zuiko Digital ED and Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF

Attribute	Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF ×	Olympus 12-40mm ƒ/2.8 Pro M.Zuiko Digital ED ×
Aperture (f)	2.80 - 32.00	2.80 - 22.00
Diaphragm Blades Type	-	circular
Filter Size (mm)	67	62
Notes	Available AF mounts: Canon, Konica Minolta, Nikon, Pentax; Includes petal type lens hood.	Dust and Splash-proof
Focus Details	Internal	-
Type	Standard Zoom	Standard Zoom
Diaphragm Blades	7	7
Diameter (mm)	74	70
Image Circle	Image Circle	Image Circle
Focal Length (mm)	17.00 - 50.00	12.00 - 40.00
Brand	Tamron	Olympus
Name	Tamron SP AF 17-50mm f/2.8 XR Di II LD Aspherical IF	Olympus 12-40mm ƒ/2.8 Pro M.Zuiko Digital ED
Weight (g)	398	382
Diagonal Angle of View (degree)	31.20 - 78.80	30.00 - 84.00
Lens Construction	16 elements in 13 groups, including Low Dispersion and Aspherical elements	14 elements in 9 groups, including 1 aspherical ED element, 2 aspherical elements, 1 DSA element, 2 ED element, 1 HD element, and 2 HR elements
Zoom System	Rotary	Rotary
Closest Focus (m)	0.27	0.2
35mm Equivalent	-	24 - 80mm
Length (mm)	81.7	84
APS Equivalent	1.5x: 25.5 - 75mm; 1.6x: 27.2 - 80mm	-
Magnification Ratio (x)	0.22	0.3