Pentax Prototype Prime Lenses

Table 1. Pentax Prototype Prime Lenses.
Lens	Elements- Groups	Min. Focus Distance (m)	Filter Dia- meter (mm)	Lens Diameter x Length (mm)	Weight (g)	In Production
K 8.4/2.8 Bird's-Eye	10-7	—	—	unknown x unknown	unknown	no
K 20/1.4 AL	11-10	0.25	77	80 x 65	445	no
Takumar-DA 40/2.8 AL Limited	5-4	0.4	49	63 x 15	90	no
K 300/2	unknown-unknown	unknown	150	unknown x unknown	4500	no