Optical systems and optical instruments

Claims

1. From the object side, it is composed of a front group, a stop, and a rear group. the rear group includes a focusing group that moves along the optical axis during focusing, and an image-side group that is located closer to the image plane than the focusing group and is fixed during focusing, An optical system that satisfies the following condition: 0.10 < fr / ff < 4.00 however, fr: focal length of the image-side lens group ff: focal length of the focusing group

2. It is composed of, in order from the object side, a front group, a stop, and a rear group having positive refractive power, the front group includes, in order from the object side, a first negative lens, a second negative lens, and a third negative lens; An optical system that satisfies the following condition: 0.10 < (-fL123) / fB < 0.65 however, fL123: a composite focal length of the first negative lens, the second negative lens, and the third negative lens fB: focal length of the rear group

3. the front group includes, in order from the object side, a first negative lens, a second negative lens, and a third negative lens; 2. The optical system according to claim 1, wherein the following condition is satisfied: 0.10 < (-fL123) / fB < 0.65 however, fL123: a composite focal length of the first negative lens, the second negative lens, and the third negative lens fB: focal length of the rear group

4. 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.50 < DSI / DL1S < 1.00 however, DSI: Distance on the optical axis from the aperture to the image plane DL1S: the distance on the optical axis from the lens surface in the front group closest to the object to the stop

5. 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.40 < DSLR / DL1S < 0.95 however, DSLR: the distance on the optical axis from the stop to the lens surface in the rear group closest to the image plane DL1S: the distance on the optical axis from the lens surface in the front group closest to the object to the stop

6. 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.75 < fA / fB < 4.20 however, fA: focal length of the front group fB: focal length of the rear group

7. the front group includes, in order from the object side, a first negative lens, a second negative lens, and a third negative lens; 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.05 < (-fL123) / fA < 0.55 however, fL123: a composite focal length of the first negative lens, the second negative lens, and the third negative lens fA: focal length of the front group

8. the front group includes, in order from the object side, a first negative lens, a second negative lens, and a third negative lens; the rear group includes a focusing group that moves along the optical axis during focusing, and an image-side group that is located closer to the image plane than the focusing group and is fixed during focusing, 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.10 < (-fL123) / fr < 0.40 however, fL123: a composite focal length of the first negative lens, the second negative lens, and the third negative lens fr: focal length of the image-side lens group

9. 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.10 < fA / TL < 0.70 however, fA: focal length of the front group TL: total optical length of the optical system

10. 4. The optical system according to claim 1, wherein the following condition is satisfied: 50.00° < ω < 67.00° however, ω: half angle of view of the optical system

11. 4. The optical system according to claim 1, wherein the following condition is satisfied: 0.27 < BF / Ymax < 1.84 however, BF: back focus of the optical system Ymax: maximum image height of the optical system

12. 4. The optical system according to claim 1, wherein the following condition is satisfied: -0.10 < D however, D: Amount of distortion at the outermost periphery

13. An optical instrument comprising the optical system according to any one of claims 1 to 3.