Inner focus lens system, interchangeable lens apparatus and camera system
View Patent ↗An inner focus lens system comprising a first lens unit and subsequent lens units, wherein the first lens unit: is fixed with respect to an image surface in focusing; and includes a first positive lens element located closest to the object side and a second positive lens element, the subsequent lens units include only a first focusing lens unit located closest to the object side and a second focusing lens unit, at least one of the first focusing lens unit and the second focusing lens unit is composed of two or less lens elements, and the subsequent lens units include an image blur compensating lens unit.
1. An inner focus lens system, in order from an object side to an image side, comprising a first lens unit, and subsequent lens units, wherein
the first lens unit is fixed with respect to an image surface in focusing from an infinity in-focus condition to a close-object in-focus condition,
the first lens unit includes: a first positive lens element being located closest to the object side, and having positive optical power; and a second positive lens element having positive optical power,
the subsequent lens units include only a first focusing lens unit located closest to the object side, and a second focusing lens unit, as focusing lens units that move along an optical axis in the focusing,
at least one of the first focusing lens unit and the second focusing lens unit is composed of two or less lens elements, and
the subsequent lens units include an image blur compensating lens unit that moves in a direction perpendicular to the optical axis to optically compensate image blur.
2. The inner focus lens system as claimed in claim 1 , wherein the following condition (1) is satisfied:
vd L1 <35 (1)
where
vd L1 is an Abbe number to the d-line of the first positive lens element.
3. The inner focus lens system as claimed in claim 1 , wherein the following condition (2) is satisfied:
nd L1 >1.8 (2)
where
nd L1 is a refractive index to the d-line of the first positive lens element.
4. The inner focus lens system as claimed in claim 1 , wherein the following condition (3) is satisfied:
1 <|f F1 /f F2 |<3 (3)
where
f F1 is a focal length of the first focusing lens unit, and
f F2 is a focal length of the second focusing lens unit.
5. The inner focus lens system as claimed in claim 1 , wherein the following condition (4) is satisfied:
0.1 <|f OIS /f A |<2 (4)
where
f OIS is a focal length of the image blur compensating lens unit, and
f A is a focal length of the entire inner focus lens system.
6. The inner focus lens system as claimed in claim 1 , wherein the following condition (5) is satisfied:
0.1 <|f OIS /f F1 |<1.2 (5)
where
f OIS is a focal length of the image blur compensating lens unit, and
f F1 is a focal length of the first focusing lens unit.
7. The inner focus lens system as claimed in claim 1 , wherein the following condition (6) is satisfied:
0.3 <|f G1 /f F1 |<1.1 (6)
where
f G1 is a focal length of the first lens unit, and
f F1 is a focal length of the first focusing lens unit.
8. The inner focus lens system as claimed in claim 1 , wherein the following condition (7) is satisfied:
| TH F2 /f A |<0.05 (7)
where
TH F2 is an optical axial thickness of the second focusing lens unit, and
f A is an focal length of the entire inner focus lens system.
9. An interchangeable lens apparatus comprising:
an inner focus lens system as claimed in claim 1 ; and
a lens mount section which is connectable to a camera body including an image sensor for receiving an optical image formed by the inner focus lens system and converting the optical image into an electric image signal.
10. A camera system comprising:
an interchangeable lens apparatus including an inner focus lens system as claimed in claim 1 ; and
a camera body which is detachably connected to the interchangeable lens apparatus via a camera mount section, and includes an image sensor for receiving an optical image formed by the inner focus lens system and converting the optical image into an electric image signal.
11. An inner focus lens system, in order from an object side to an image side, comprising a first lens unit, and subsequent lens units, wherein
the first lens unit is fixed with respect to an image surface in focusing from an infinity in-focus condition to a close-object in-focus condition,
the first lens unit includes: a first positive lens element being located closest to the object side, and having positive optical power; and a second positive lens element having positive optical power,
the subsequent lens units include at least a first focusing lens unit located closest to the object side, and a second focusing lens unit, as focusing lens units that move along an optical axis in the focusing,
the subsequent lens units include an image blur compensating lens unit that moves in a direction perpendicular to the optical axis to optically compensate image blur, and
the following condition (8) is satisfied:
L A /f A <1.2 (8)
where
L A is an overall length of the inner focus lens system (a distance from an object side surface of the first positive lens element to the image surface), and
f A is a focal length of the entire inner focus lens system.
12. The inner focus lens system as claimed in claim 11 , wherein the following condition (1) is satisfied:
vd L1 <35 (1)
where
vd L1 is an Abbe number to the d-line of the first positive lens element.
13. The inner focus lens system as claimed in claim 11 , wherein the following condition (2) is satisfied:
nd L1 >1.8 (2)
where
nd L1 is a refractive index to the d-line of the first positive lens element.
14. The inner focus lens system as claimed in claim 11 , wherein the following condition (3) is satisfied:
1 <|f F1 /f F2 |<3 (3)
where
f F1 is a focal length of the first focusing lens unit, and
f F2 is a focal length of the second focusing lens unit.
15. The inner focus lens system as claimed in claim 11 , wherein the following condition (4) is satisfied:
0.1 <|f OIS /f A |<2 (4)
where
f OIS is a focal length of the image blur compensating lens unit, and
f A is the focal length of the entire inner focus lens system.
16. The inner focus lens system as claimed in claim 11 , wherein the following condition (5) is satisfied:
0.1 <|f OIS /f F1 |<1.2 (5)
where
f OIS is a focal length of the image blur compensating lens unit, and
f F1 is a focal length of the first focusing lens unit.
17. The inner focus lens system as claimed in claim 11 , wherein the following condition (6) is satisfied:
0.3 <|f G1 /f F1 |<1.1 (6)
where
f G1 is a focal length of the first lens unit, and
f F1 is a focal length of the first focusing lens unit.
18. The inner focus lens system as claimed in claim 11 , wherein the following condition (7) is satisfied:
| TH F2 /f A |<0.05 (7)
where
TH F2 is an optical axial thickness of the second focusing lens unit, and
f A is the focal length of the entire inner focus lens system.
19. An interchangeable lens apparatus comprising:
an inner focus lens system as claimed in claim 11 ; and
a lens mount section which is connectable to a camera body including an image sensor for receiving an optical image formed by the inner focus lens system and converting the optical image into an electric image signal.
20. A camera system comprising:
an interchangeable lens apparatus including an inner focus lens system as claimed in claim 11 ; and
a camera body which is detachably connected to the interchangeable lens apparatus via a camera mount section, and includes an image sensor for receiving an optical image formed by the inner focus lens system and converting the optical image into an electric image signal.