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Description  |
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BACKGROUND OF THE INVENTION
The present invention relates to photographic cameras. In particular, it
relates to a photographic camera having at least two different lenses
which can selectively be placed in operating position.
When it is desired to change a camera from normal picture taking to
telephotography, and vice versa, the focal length of its objective --
i.e., its lens -- must be changed. In motion-picture cameras this is now
usually accomplished by using a variable-focus objective, a so-called
"zoom lens", although it is also known to provide a carrier on which two
or more lenses of different focus are mounted and which can be
appropriately shifted or rotated in order to place the respectively
desired lens in operating position. Such arrangements are also known for
still cameras.
Predictably, it has now been proposed to equip small still cameras using
"type 110" film cassettes, popularly known as "pocket cameras", with a
telephotography capability. The dimension of these cameras can be small
and their shape flat, due to the size and shape of the film cassettes they
use. Since it is desired to avoid exceeding the dimensions of the housing,
it has been proposed to mount two different lenses on a slidable carrier
and to integrate the resulting assembly within the camera housing.
This basic concept is attractice; however, difficulties are experienced
when it is attempted to translate the concept into technical reality. If
the camera is of the type which permits the user to set the distance to
the subject being photographed, which is done by moving the lenses
lengthwise of the optical axis of the camera, then the two lenses -- due
to their different focal lengths -- must be moved lengthwise of the
optical axis by different distances even though in both instances the
distance to the subject being photographed is the same. In other words: if
the lens for normal photography is set to focus, e.g., on a subject 10
feet from the camera, this setting is incorrect for the telephoto lens
because of the different focal length of the same. This relationship is
always true, except if the distance is set for infinity. The result is
that for all settings except infinity the distance setting must be changed
whenever the user switches from one to the other lens. This is at least
bothersome for the user, and can often lead to ruined exposures when the
user changes from one lens to the other but forgets to reset the distance.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to overcome the
aforementioned problems.
More particularly, it is an object of the invention to provide a camera
having two or more selectively usable lenses and avoiding these problems.
Such a camera may be of the type using "110" film cassettes, but the
invention is not restricted to this type of camera.
A still more specific object is to provide such a camera as outlined above,
which is provided with a simple distance-setting instrumentality and in
which the distance set for the purpose of focusing one of the lenses is
automatically correct also for the other lens or lenses.
Briefly stated the invention is embodied in a photographic camera having an
optical axis and comprising at least two different photographic lenses; a
lens carrier mounting the lenses; means mounting the lens carrier for
displacement in a direction normal to the axis between respective
lens-changing first settings in each of which a different one of the
lenses is located on the optical axis, and also for displacement in a
direction lengthwise of the axis to different second settings
corresponding to different focal lengths; means for selecting respective
ones of the second settings; and means responsive to operation of the
selecting means for displacing the lens carrier lengthwise of the optical
axis through distances which differ for each of the second settings in
dependence upon the respective first setting assumed by the lens carrier.
The novel features which are considered as characteristic for the invention
are set forth in particular in the appended claims. The invention itself,
however, both as to its construction and its method of operation, together
with additional objects and advantages thereof, will be best understood
from the following description of the specific embodiments when read in
connection with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a somewhat diagrammatic partial top-plan view, showing a camera
embodying the invention with the normal lens in operating position and
focused for infinity;
FIG. 2 is the same view as FIG. 1, but showing the normal lens focused for
a close-up picture; and
FIG. 3 is a view similar to that of FIG. 1, but showing the telephoto lens
in operating position.
DESCRIPTION OF A PREFERRED EMBODIMENT
The drawing illustrates only those parts of a camera using type "110" film
cassettes, which are essential to an understanding of the invention. It
also shows the camera as having two different lenses, but it should be
understood that the invention is equally applicable to cameras having more
than two different lenses.
With the above in mind, it will be seen that in all Figures of the drawing
the camera has a housing 1 for a type "110" film cassette 2. The latter
has a film window 3 and accommodates a supply of film which is
incrementally moved into registry with the film window 3 so that the film
portion thus located opposite the window 3 can be exposed through
whichever one of the lenses 5 and 6 is in the operating position. The
mechanism for transporting the film in cassette 2 is not illustrated; it
forms no part of the invention and is known per se.
The lens 6 is a telephoto lens whereas lens 5 is a normal lens, to be
employed when it is not desired to make telephoto shots. To be selectively
movable to operating position in which they are located on the optical
axis of the camera, i.e., opposite the film window 3, the lenses 5 and 6
are mounted on a lens carrier 4 which is movable in direction transverse
to the optical axis of the camera -- i.e., in the plane of the drawing --
through a distance corresponding to the spacing between the optical axis O
of lens 5 and the optical axis O' of lens 6. Since FIGS. 1 and 2 show lens
5 in operating position, its optical axis O coincides with the optical
axis of the camera.
In addition, the carrier 4 is also movable longitudinally of the optical
axis of the camera, i.e., inwardly and outwardly with respect to the
housing 1; this movement can take place through a distance which is at
least equal to the extent to which the telephoto lens 6 must be moved
outwardly of housing 1, i.e., extended, for close-up shots.
The movements of these components are controlled by an operating member 7
which is mounted on housing 1 to be turnable together with a scale or dial
7a relative to a fixed marker 7b on the housing. A control cam 8 is
fixedly connected to the member 7 so as to turn with the same. A follower
arm 9 is mounted on a stationary pin 10 to be turnable about the same. The
arm has an end portion which is in tracking engagement with the cam 8; its
other end portion is pivoted to a transmission member 11 which is secured
to carrier 4 so as to be turnable about an axis 12.
The camera shutter 14 is shown only diagrammatically since its construction
forms no part of the invention and is known per se. It is located in the
region intermediate the front lens component of the normal lens 5 and the
rear lens component of the telephoto lens 6 and it goes without saying
that the components of the shutter 14 and its operating elements must not
interfere with the movement of carrier 4 transverse to and lengthwise of
the optical axis of the camera.
The operation:
To set the distance a user turns the member 7 until the appropriate symbol
on dial 7a is located opposite the marker 7b. This results in
corresponding turning of the cam 8 which effects turning of arm 9 about
axis 10 and displacement of the transmission member 11 through distance a
to the position shown in FIG. 2. The movement of member 11 is a composite
movement, which is to say that part of the turning movement of arm 9 is
converted into a rotary motion of member 11 whereas another part of the
turning movement of arm 9 is converted into a sliding motion of member 11
in direction of the optical axis of the camera. Only the latter motion is
relevant for displacement of the carrier 4 by the amount n, i.e., the
distance which is required to set the normal lens 5 to the position in
FIG. 2 for photographing a subject spaced from the camera by a distance
of, say 1 m.
If the user desires to change lenses, e.g., to switch from the normal lens
5 in use in FIG. 2 to the telephoto lens 6 which is shown in use in FIG.
3, he moves a handle 13 which is accessible at the outside of housing 1
from setting N (normal) to setting T (telephoto). This moves the carrier 4
to the position shown in FIG. 3 in which it is now the telephoto lens 6
which is located opposite the film window 3. At this time member 11
extends parallel to the optical axis of the camera, rather than being
inclined thereto as before; this means that the previously mentioned
displacement a is now fully converted into a displacement t of the carrier
4. It should be noted that the displacement t is greater than the
displacement n, being selected to afford the focal length increase which
is required for the telephoto lens 6 in all distance settings of the same,
i.e., for close-up shots, far shots and intermediate shots. Since shutter
14 is stationarily mounted in housing 1, it is unaffected by any
displacement of carrier 4.
From the description above it will be clear that only a single
distance-setting member 7 is required. It sets the longest focal length as
the measure a and transmits it via carrier 4 to whatever lens is in
operating position; if a shorter focal length is to be set, the measure a
is transmitted to carrier 4 appropriately reduced. A change-over from one
lens to the other results automatically in a corresponding change in the
position of carrier 4 lengthwise of the optical axis of the camera and
thus does not require resetting of the member 7. In other words: once the
distance has been set for either one of lenses 5, 6 a switch to the other
lens will automatically result in appropriate compensation and adjustment
of the focal length of the newly-selected lens.
It is clear that the invention disclosed herein is susceptible of various
modifications. For example, three or more different lenses could be
mounted on the carrier 4, having focal lengths which differ in accordance
with the respective angle of inclination of the member 11 relative to the
optical axis of the camera, and hence of the lens which at any given time
is in operating position. In such a case the lens having the greatest
focal length would be associated with the position of member 11 in which
the latter extends substantially parallel to the optical axis.
It will be understood that each of the elements described above, or two or
more together, may also find a useful application in other types of
applications differing from the types described above.
While the invention has been illustrated and described as embodied in a
pocket camera, it is not intended to be limited to the details shown,
since various modifications and structural changes may be made without
departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of
the present invention that others can, by applying current knowledge,
readily adapt it for various applications without omitting features that,
from the standpoint of prior art, fairly constitute essential
characteristics of the generic or specific aspects of this invention.
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