Photography – Camera detail – Hood
Reexamination Certificate
2000-04-20
2001-07-31
Gray, David M. (Department: 2851)
Photography
Camera detail
Hood
C396S544000
Reexamination Certificate
active
06269227
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a lens hood, particularly to a lens hood suitable for use on camera lenses.
Camera lenses are usually supplied with a lens hood for shielding rays of light coming from outside the picture area, or outside the angle of view of the lens, and it is mounted at the front end of the lens barrel. In order to enhance the photographic effect of a camera lens, it is also common practice to mount a polarizing filter, crossed filters and various other filters at the front end of the lens barrel. In the case of a polarizing filter, the position of its rotation about the optical axis is changed to limit the amount of polarized light from the subject so as to produce a sharper picture. In the case of crossed filters, the position of their rotation about the optical axis is changed to alter the direction of a blurred cross. These filters that create varying photographic effects by changing the direction of rotation about the optical axis are hereunder referred to as “rotatory effect filters”. If they are used on a single-lens reflex camera, their effectiveness can be confirmed by looking through a viewfinder and, therefore, the aforementioned lens hood which is to be mounted at the front end of the lens barrel is so adapted that pictures can be taken with the lens hood attached to the lens barrel and as those filters are rotated.
FIG. 15
is a partial section of the lens hood used in combination with a polarizing filter as a rotatory effect filter. The polarizing filter generally indicated by
20
comprises a movable frame
22
that supports the rim of a disk-shaped optical filter glass
24
and a fixed frame
21
which supports said movable frame
22
in such a way that it can rotate about the optical axis. Said fixed frame
21
has a male thread
23
formed on the outer periphery and by bringing it into engagement with a female thread
11
formed on the inner periphery at the front end of a lens mount
10
, the fixed frame
21
can be fitted on the lens mount
10
. Once the fixed frame
21
has been fitted, the movable frame
22
can be rotated relative to said fixed frame
21
so that the rotation of the polarizing filter
20
about the optical axis is adjustable to a desired position. A lens hood
30
A is fitted around the front end of the lens mount
10
and it may be of a bayonet type.
In order to ensure that the rotatory effect filter, which is the polarizing filter
20
in the case under consideration, can be rotated with the lens hood
30
A fitted on the lens mount
10
, the lens hood
30
A is formed to have a sufficiently larger outside diameter than the lens mount
10
that a wide enough space to permit the passage of fingertips of a photographer is formed around the polarizing filter
20
. When taking pictures with the polarizing filter
20
fitted in the lens hood
30
A, the photographer puts the finger into the lens hood
30
A through the front opening and rotates the polarizing filter
20
relative to the lens mount
10
by manipulating the movable frame
22
with the finger.
A problem with the lens hood
30
A is that while the photographer manipulates the polarizing filter
20
with one hand while looking at the subject through the viewfinder, the hand which has been put into the lens hood
30
A through the front opening hides a portion of the lens mount
10
to cause occasional vignetting in the field of view and this is by no means desirable for the purpose of checking for the appropriateness of the picture area. As a further problem, in order to ensure the space through which the finger can be put into the lens hood
30
A, its outside diameter is prone to be unduly larger than that of the lens mount but this is not desirable from portability and design viewpoints.
To solve this problem, the idea shown in
FIG. 16
was proposed; an opening
35
or a hole through which a photographer's finger can be put into a lens hood
30
B is made in a selected area of the lens hood
30
B and the photographer manipulates a polarizing filter
20
by rotating it via the opening. With this lens hood
30
B, there is no need to provide a space around the polarizing filter
20
into which the finger can be put and this not only reduces the outside diameter of the lens hood
30
B but also prevents the field of view through the viewfinder from being blocked by the photographer s hand with which the polarizing filter
20
is being adjusted. On the other hand, however, when the photographer removes the finger out of the lens hood
30
B and performs the actual shooting by, for example, releasing the shutter, rays outside the angle of view will get into the lens mount
10
through the opening
35
and the intended function of the lens hood is not fulfilled.
SUMMARY OF THE INVENTION
An object, therefore, of the present invention is to provide a lens hood that is reduced in outside diameter while allowing for easy manipulation when adjusting a polarizing filter and other components mounted on the lens barrel and which yet can perform its intended function to the fullest extent.
To attain this object, the present invention provides a lens hood to be fitted on a lens mount of a camera in such a way as to surround the front end of the lens barrel, said lens hood having an opening made in at least a portion of its peripheral surface to help manipulate the component mounted at the front end of said lens barrel and a lid for closing said opening, said lid being formed as a separate entity from said lens hood and retained on said lens hood such that it is movable between one position and another relative to said lens hood, said lid being so adapted that it closes said opening when it has moved to said one position while making said opening open when it has moved to said another position.
In a preferred embodiment of the invention, said lid is linked to said lens hood by means of a hinge structure that causes said lid to turn radially of said lens hood and said lid makes said opening open when it has been turned radially outward while closing said opening when it has been turned in a direction parallel to the peripheral surface of said lens hood. In a first preferred embodiment of the invention, said hinge structure comprises a shaft element for providing a hinge link between said lid and said lens hood and an elastic means for-urging said lid toward a direction in which it opens, said lid and said lens hood being supplied with a retainer means for keeping said lid in said closed state. In a second preferred embodiment of the invention, said hinge structure is composed of a pin shaft provided on either said lid or said lens hood and pin shaft receptacles provided on said lens hood or said lid, said lid and said lens hood being provided with engagement means for engaging said lid in said open state and said closed state, respectively. In a third preferred embodiment of the invention, said lid is retained by rail structures capable of movement relative to said lens hood along the axis of the tube of said lens hood, and said lid, when it has moved to said one position, is in a position that closes said opening and, when it has moved to said another position, it is in a position adjacent said opening in the axial direction of the tube of said hood to make said opening open.
The lens hood of the invention has an opening through which the photographer's finger is put into the lens hood to enable adjustment of a polarizing filter and other components mounted on the lens barrel. When there is no need to adjust the polarizing filter or any other component on the lens barrel, the opening is closed with the lid to prevent rays outside the angle of view from getting into the lens barrel, thereby ensuring the intended shielding effect of the lens hood. Even when the lid is in a non-closing position, it is retained on the lens hood and there is no possibility of losing it. Note that the lid might be lost if it is of such a type that it has to be detached from the lens hood to make the opening open. In the present invention, the lid may be so designed tha
Hamasaki Takuji
Hattori Kazuhiro
Iikawa Makoto
Ishizuka Kazunori
Suzuki Hiroaki
Asahi Kogaku Kogyo Kabushiki Kaisha
Gray David M.
Greenblum & Bernstein P.L.C.
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