Image magnification control device for a camera

Claim 2

An image magnification control device for a camera, which controls the image magnification to be a set magnification, said device comprising: defocus information detection means for detecting a defocus information by using a light having passed through the photographic lens; computation means for computing a control focal length, which is required to maintain the image magnification at the set magnification, based upon the defocus information detected by said detection means; and focal length control means for changing a focal length of the photographic lens so as to meet said control focal length.

Claim 3

The image magnification control device according to claim 1, wherein said defocus information comprises a defocus amount and a defocus direction of the photographic lens of a photographic lens with respect to an ideal focal plane.

Claim 4

The image magnification control device according to claim 1 or 2,wherein said image magnification setting means comprises an external setting means to set the image magnification from outside the camera.

Claim 5

An image magnification control device for a camera comprising: distance detection means for detecting a distance "X₀" between a rear focal point of a photographic lens and an in-focus position from the delivery-amount of a focusing lens; defocus information detection means for detecting a defocus information "dx" of photographic lens by using a light having passed through the photographic lens; focal length detection means for detecting a focal length "f₀" of the photographic lens; image magnification setting means for setting an image magnification "m₀" for taking a photogtraph; computation means for computing a control focal length "f₁" in accordance with an equation: using said x₀, d x , f₀ and m₀; and; focal length control means for changing focal length of the photographic lens so as to meet said control focal length.

Claim 6

An image magnification control device for a camera comprising: distance detection means for detecting a distance "X₀" between a rear focal point of a photographic lens and an in-focus position from the delivery-amount of a focusing lens; defocus information detection means for detecting a defocus information "dx" of photographic lens by using a light having passed through the photographic lens; focal length detection means for detecting a focal length "f₀" of the photographic lens; image magnification setting means for setting an image magnification "m₀" for taking a photogtraph; computation means for computing a control focal length "f₁" in accordance with an equation: using said x₀, d x , f₀ and m₀; and; focal length control means for changing focal length of the photographic lens so as to meet said control focal length.

Claim 7

An image magnification control device for a camera comprising: image magnification setting means for setting an image magnification to a certain magnification; focal length detection means for detecting a focal length of a photographic lens; focal length control means for controlling the focal length of said photographic lens so as to maintain the image magnification set by said image magnification setting means; and determining means for determining whether the set image magnification is in a controllable range with the present focal length detected by said detection means.

Claim 8

An image magnification control device for a camera comprising: image magnification setting means for setting an image magnification to a certain magnification; focal length detection means for detecting a focal length of a photographic lens; focal length control means for controlling the focal length of said photographic lens so as to maintain the image magnification set by said image magnification setting means; and determining means for determining whether the set image magnification is in a controllable range with the present focal length detected by said detection means.

Claim 9

The image magnification control device according to any­one of the foregoing claims, which further comprises inhibit means for inhibiting a shutter-release operation until said focal length comes into a range wherein said set image magnification can be obtained, when it is determined by said determining means that said image magnification is out of said controllable range.

Claim 10

The image magnification control device according to any­one of the foregoing claims, which further comprises inhibit means for inhibiting the image magnification control by disabling said focal length control means until said focal length comes into a range wherein said set image magnification can be obtained, when it is determined by said determining means that said image magnification is out of said controllable range.

Claim 11

The image magnification control device according to any­one of the foregoing claims, which further comprises indication means for indicating of warning, when it is determined by said determining means that said image magnification is out of said controllable range.

Claim 12

An image magnification control device for a camera, comprising: focus-driving means for driving a photographic lens for focusing; zoom-driving means for driving said photographic lens for zooming; image magnification setting means for setting an image magnification to a certain magnification; focal length detection means for detecting a focal length of the photographic lens; determining means for determining whether the image magnification set by said image magnification is in a controllable range with the present focal length detected by said detection means; and control means for controlling said zoom-driving means to maintain the image magnification set by said image magnification setting means, wherein said control means disables at least one of said zoom-driving means and said focus-driving means when it is determined by said determining means that said image magnification is out of said controllable range until it is determined by said determining means that the focal length comes back in a range wherein said set image magnification can be obtained.

Claim 13

An image magnification control device for a camera, comprising: focus-driving means for driving a photographic lens for focusing; zoom-driving means for driving said photographic lens for zooming; image magnification setting means for setting an image magnification to a certain magnification; focal length detection means for detecting a focal length of the photographic lens; determining means for determining whether the image magnification set by said image magnification is in a controllable range with the present focal length detected by said detection means; and control means for controlling said zoom-driving means to maintain the image magnification set by said image magnification setting means, wherein said control means disables at least one of said zoom-driving means and said focus-driving means when it is determined by said determining means that said image magnification is out of said controllable range until it is determined by said determining means that the focal length comes back in a range wherein said set image magnification can be obtained.

Claim 14

An image magnification control device for a camera wherein either a single-shot photographing mode or a sequential-shots photographing mode can be is selected, said device comprises: image magnification setting means for setting image magnification to a certain magnification; and control means for driving a photographic lens so as to maintain the image magnification set by said image magnification setting means, wherein said control means drives said photographic lens, in case the sequential-shots mode is selected, in such a fashion that once a subject is focused at the image magnification set by said image magnification setting means in the sequential-shots photographing mode, focusing operation is sequentially performed at the set image magnification as the subject moves.

Claim 15

An image magnification control device for a camera wherein either a single-shot photographing mode or a sequential-shots photographing mode can be is selected, said device comprises: image magnification setting means for setting image magnification to a certain magnification; and control means for driving a photographic lens so as to maintain the image magnification set by said image magnification setting means, wherein said control means drives said photographic lens, in case the sequential-shots mode is selected, in such a fashion that once a subject is focused at the image magnification set by said image magnification setting means in the sequential-shots photographing mode, focusing operation is sequentially performed at the set image magnification as the subject moves.

Claim 16

An image magnification control device for a camera wherein either a focus-priority mode or a shutter-release-priority mode can be selected, said device comprises: image magnification setting means for setting image magnification to a certain magnification; and control means for driving a photographic lens so as to maintain the image magnification set by said image magnification setting means, wherein said control means executes focus-lock operation when a subject is focused in the focus-­priority mode while the image magnification has not been set, and wherein said control means executes image magnification control without executing focus-lock operation when a subject is focused in the focus-­priority mode while the image magnification has been set by said image magnification setting means.

Claim 17

An image magnification control device for a camera wherein either a focus-priority mode or a shutter-release-priority mode can be selected, said device comprises: image magnification setting means for setting image magnification to a certain magnification; and control means for driving a photographic lens so as to maintain the image magnification set by said image magnification setting means, wherein said control means executes focus-lock operation when a subject is focused in the focus-­priority mode while the image magnification has not been set, and wherein said control means executes image magnification control without executing focus-lock operation when a subject is focused in the focus-­priority mode while the image magnification has been set by said image magnification setting means.