OPTICAL APPARATUS

• US 20080037092A1
• Filed: 05/07/2007
• Published: 02/14/2008
• Est. Priority Date: 05/23/2006
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Umezu, Takuji, Ichinose, Harunobu
• Granted Patent: US 8,120,865 B2
• Time in Patent Office: Days
• US Class Current: 359/227
• CPC Class Codes: G02B 26/023 comprising movable attenuating elements, e.g. neutral density filters
• CPC Class Codes: G02B 5/205 Neutral density filters
• CPC Class Codes: G03B 11/00 Filters or other obturators specially adapted for photographic purposes
• CPC Class Codes: G03B 7/10 a servo-motor providing energy to move the setting member
• CPC Class Codes: G03B 9/06 Two or more co-operating pivoted blades, e.g. iris type shutters functioning as diaphragms by limiting extent of opening movement G03B9/08

Abstract

An optical apparatus is disclosed which is capable of preventing degradation of image quality caused by an ND filter. The optical apparatus includes an aperture stop having an aperture variable in size, and an ND filter movable with respect to the aperture of the aperture stop, an actuator that drives the ND filter, and a controller that controls the actuator. The ND filter includes a part having a size that can fully cover a first aperture that is the aperture with the aperture stop being narrowed. The controller controls the actuator so that the ND filter is moved without a halt between a first position where the part is retracted with respect to the first aperture with the aperture stop being narrowed, and a second position where the part fully covers the first aperture in any stop operation.

Claims

1. An optical apparatus comprising:

an aperture stop having an aperture variable in size;

an ND filter movable with respect to the aperture of the aperture stop;

an actuator that drives the ND filter; and

a controller that controls the actuator,

wherein the ND filter includes a part having a size that can fully cover a first aperture that is the aperture with the aperture stop being narrowed, and

the controller controls the actuator so that the ND filter is moved without a halt between a first position where the part is retracted with respect to the first aperture and a second position where the part fully covers the first aperture in any stop operation.

2. The optical apparatus according to claim 1, wherein the part has a transmittance of 75% or more.

3. The optical apparatus according to claim 1, wherein the part includes a portion having a transmittance of 75% or more, and a portion adjacent to the portion having the transmittance of 75% in a movement direction of the ND filter and having a transmittance of less than 75%.

4. The optical apparatus according to claim 1, wherein the controller controls the actuator so as to move the ND filter from the first position to the second position according to a first photometric value, and move the ND filter from the second position to the first position according to a second photometric value different from the first photometric value.

5. The optical apparatus according to claim 4, wherein the controller controls the aperture stop so as to change the size of the aperture when the photometric value changes between the first photometric value and the second photometric value in a state in which the ND filter is located at the second position.

6. The optical apparatus according to claim 4, further comprising an image-pickup element that photoelectrically converts an object images,

wherein the controller performs control to change an electronic shutter speed of the image-pickup element when the photometric value changes between the first photometric value and the second photometric value in a state in which the ND filter is located at the second position.

7. The optical apparatus according to claim 1, wherein the ND filter includes a first part having a certain transmittance and a second part having a transmittance lower than that of the first part, the first part having a size that can fully cover a first aperture that is the aperture with the aperture stop being narrowed, and

the controller controls the actuator so as to move the ND filter in any stop operation without a halt between the first position where the first part is fully retracted with respect to the first aperture and the second position where the first part fully covers the first aperture.

8. An optical apparatus comprising:

an aperture stop having an aperture variable in size; and

an ND filter movable with respect to the aperture of the aperture stop;

wherein when a movement direction of the ND filter for covering the aperture is a first direction, and a direction parallel to light entrance/emergence surfaces of the ND filter and perpendicular to the first direction is a second direction, a tip of the ND filter in the first direction has a shape different from a linear shape extending in the second direction.

9. An optical apparatus comprising:

an aperture stop having an aperture variable in size; and

an ND filter movable with respect to the aperture of the aperture stop;

wherein when a movement direction of the ND filter for covering the aperture is a first direction, and a direction parallel to a scanning line direction of an image-pickup element that converts an optical image formed by light having passed through the aperture of the aperture stop into an electrical signal is a second direction, and a tip of the ND filter in the first direction has a shape different from a linear shape extending in the second direction.