JP H04-110811 A — Takehisa Koyama
| 9 ELEMENTS / 6 GROUPS |
| DESIGN f = 174.86 mm |
| DESIGN F/5.71 |
| ALL SPHERICAL |
| PUBLISHED 0.5× CLOSE-FOCUS STATE |
PUBLISHED floating inner focus: G1 and G4 are fixed, and from infinity to 0.5× G2 moves 11.18 mm toward the image while G3 moves 8.25 mm toward the object; the stop between them does not move. Both end states are the patent's printed gaps, and positions in between are linearly interpolated. The 0.5× state puts the object 403.0 mm in front of the first surface, about 0.546 m from object to image against the marketed 0.55 m minimum focus. Real rays focus that state on the fixed image plane to within about 0.04 mm; the paraxial image lies 0.288 mm behind it because of the design's spherical aberration at 1:2.
| Element | Type | Glass |
|---|---|---|
| E1 | Biconvex Positive | FCD1 equivalent (HOYA) |
| E2 | Biconvex Positive | FCD1 equivalent (HOYA) |
| E3 | Biconcave Negative | NBFD10 equivalent (HOYA) |
| E4 | Positive Meniscus | FDS90-SG equivalent (HOYA) |
| E5 | Biconcave Negative | NBFD11 equivalent (HOYA) |
| E6 | Negative Meniscus | E-FD4 / E-FD4L equivalent (HOYA) |
| E7 | Biconvex Positive | FC5 equivalent (HOYA) |
| E8 | Biconcave Negative | LAC8 equivalent (HOYA) |
| E9 | Positive Meniscus | FDS90-SG equivalent (HOYA) |