Ricoh Patent for Pentax 18mm f/1.8 Macro Lens

Ricoh filed a patent for a Pentax 18mm f/2.8 Macro lens in Japan. The new patent describes a Pentax 18mm f/1.8 lens designed for mirrorless cameras with 1/1.7-inch-type sensors.

The lens offers a wide-angle focal length of 18mm but when used with the 1/1.7-inch sensor cameras it will become a 35mm equivalent of about 84mm focal length.

More details for the patented Pentax 18mm f/1.8 lens aimed at Q-mount cameras can be seen below.

Pentax 18mm f/1.8 Macro Lens Patent

Explanation self interpretation of patent literature

• Patent Publication No. 2015-4717
  • Published 2015.1.8
  • Filing date 2013.6.19
• Example
  

  embodiment

  Example	Fno.	Focal distance	Magnification	Angle of view	Full length	Lens constitution	ED	Fluorite / Super ED
  One	2.8	18.00 18.75 19.18	0.000 -0.217 -0.333	15.8 13.0 11.6	50.70 55.89 58.67	9 groups 10 sheets	Two	Two
  Two	2.8	22.00 22.30 22.46	0.000 -0.217 -0.333	12.9 10.8 9.8	51.80 56.44 58.92	9 groups 10 sheets	One	Two
  Three	FNO. 2.8 3.1 3.2	20.00 20.29 20.43	0.000 -0.150 -0.217	14.2 12.8 12.2	49.97 53.42 54.96	9 groups 10 sheets	Two	One
  Four	2.8	20.00 20.53 20.82	0.000 -0.217 -0.333	14.2 11.8 10.7	50.80 55.87 58.57	9 groups 10 sheets	One	Two
  Five	2.8	20.00 20.74 21.08	0.000 -0.150 -0.217	14.3 12.5 11.7	50.00 53.65 55.28	8 groups nine	0	One
  Six	2.8	20.00 20.50 20.78	0.000 -0.217 -0.333	14.2 11.7 10.6	50.80 55.86 58.56	9 groups 10 sheets	Three	0

  Image height Y = 5.00mm, BF = 1.00mm

• Ricoh patents
  • 3-group configuration of negative-positive-positive
  • Front lens formula feeding

via Egami