Comparison of Pentax SMC P-FA 300mm f/2.8 ED IF and Sigma 50-100mm f/1.8 DC HSM Art

Attribute	Pentax SMC P-FA 300mm f/2.8 ED IF ×	Sigma 50-100mm f/1.8 DC HSM Art ×
Diameter (mm)	135	94
Aperture (f)	2.80 - 32.00	1.80 - 16.00
Diagonal Angle of View (degree)	8.20	16.20 - 31.70
Filter Size (mm)	112	82
Notes	Included Accessories: Case	Available AF Mounts: Canon EF-S, Nikon F, Sigma SA; Included Accessories: Lens hood, lens caps, tripod collar. Compatible with Sigma USB Dock.
Diaphragm Blades Type	-	rounded
Type	Telephoto Prime	Telephoto Zoom
APS Equivalent	450mm	1.5x: 75 - 150mm; 1.6x: 80 - 160mm
Lens Construction	10 elements in 7 groups, including 1 ED element	21 elements in 15 groups, including 3 FLD (F Low Dispersion) glass elements, 1 SLD (Special Low Dispersion) glass element, and 1 high-refractive inde
Image Circle	35mm	APS-C
Focal Length (mm)	300.00	50.00 - 100.00
Brand	Pentax	Sigma
Name	Pentax SMC P-FA 300mm f/2.8 ED IF	Sigma 50-100mm f/1.8 DC HSM Art
Weight (g)	2660	1491
Diaphragm Blades	-	9
Length (mm)	340	170.2
Magnification Ratio (x)	-	0.15
Closest Focus (m)	2	0.95
Zoom System	-	Rotary
Focus Details	Internal	HSM (Hyper Sonic Motor) with full-time manual focus override