Here's the specs from the Pentax/Ricoh web store
LENS MOUNT: PENTAX KAF
FOCAL LENGTH: 50mm (equiv 76.5mm)
APERTURE: f/1.8
MIN APERTURE: f/22
LENS CONSTRUCTION: 6 elements in 5 groups
ANGLE OF VIEW: 31.5° (w/ PENTAX DSLR)
MIN FOCUSING DISTANCE: 1.48â?? (0.45m)
MAX MAGNIFICATION: 0.15X
FILTER DIAMETER: 52mm
DIAPHRAGM CONTROL: Fully Automatic
NUMBER OF APERTURE BLADES: 7
LENS APERTURE RING: n/a
TRIPOD ADAPTER: n/a
HOOD: RH-RA 52mm (optional)
OBJECTIVE CAP: O-LC52N
CASE: S70-70 (optional)
MAX DIAMETER X MIN LENGTH: 2.5 x 1.5" (63.0 x 38.5mm)
WEIGHT (W/O HOOD): 4.3 oz (122g) - See more at:
PentaxWebstore.com:smc PENTAX DA 50mm f/1.8 smc PENTAX DA 50mm f/1.8
Type in RH-RA in ebay and you'll get one one genuine and 4 knockoffs.