CANON EF-S 55-250mm f/4-5.6 IS

US 2008/0112063 A1 — Takahiro Hatada

12 ELEMENTS / 10 GROUPS
PATENT EFL 56.9-241.3 mm
F/4.16-5.88 PATENT ENDPOINTS
3-UNIT +/−/+ ZOOM; L2 IS UNIT
1 UD-CLASS ELEMENT

Focus Mechanism

CONSTRAINED_RECONSTRUCTION: patent ¶0081 focuses by axial L1 motion only. At Canon's 1.1 m focal-plane-to-subject MFD, code solves L1 objectward by 15.5631 / 16.1731 / 16.3937 mm at wide / middle / tele while L2, L3, and the image plane remain fixed; tele paraxial magnification is 0.31037×.

Optical Elements (12 physical)

ElementTypeGlass
L11Biconvex PositiveS-BSL7 (OHARA-equivalent; exact patent coordinate match)
L12Negative MeniscusS-LAM66 (OHARA-equivalent; exact patent coordinate match)
L13Positive MeniscusS-FPL51 (OHARA-equivalent; exact patent coordinate match)
L21Biconcave NegativeS-LAL8 (OHARA-equivalent; exact patent coordinate match)
L22Positive MeniscusUnmatched (847239 high-index flint; patent vd=23.93; nearest OHARA S-TIH53WN vd=23.86)
L23Biconcave NegativeH-ZLaF50E (CDGM-equivalent; exact patent coordinate match)
L31Biconvex PositiveS-BSM18 (OHARA-equivalent; exact patent coordinate match)
L32Biconvex PositiveS-BSM14 (OHARA-equivalent; exact patent coordinate match)
L33Positive MeniscusS-FSL5 (OHARA-equivalent; exact patent coordinate match)
L34Biconcave NegativeS-TIH53 (OHARA-equivalent; exact patent coordinate match)
L35Negative MeniscusS-LAH60 (OHARA-equivalent; exact patent coordinate match)
L36Biconvex PositiveS-TIM28 (OHARA-equivalent; exact patent coordinate match)