Improvements relating to the Adjustment of Photographic Lenses.
Year: 1891

page_text: Date of Application, 16th Nov., 1891
Complete Specification Left. 15th Aug., 1892-Accepted, 17th Sept., 1892
PROVISIONAL SPECIFICATION.
Improvements relating to the Adjustment of Photographic Lenses.
I, GERHARD RODENSTOCK, of the Optisch-occultisches Institut, Munich in the
Empire of Germany do hereby declare the nature of this invention to be as
follows:-
This invention relates to the adjustment of photographic lenses and its purpose is
to allow the lens to be adjusted for the actinic or chemical focus as well as for the
visual or optical focus.
The lens tube or tube carrying the lens or combination of lenses is movable back
and forth in a socket which may be fixed when the lens does not require optical
focal adjustment, or movable when the focal position varies according to the distance
of the object photographed and the ground glass or sensitive surface is not movable
to and from the lense.
The movement of the lens tube in its socket aforesaid is limited by any suitable
device such as a pin and slot the latter plain or provided with a right angled recess
or recesses, or a spring, or spring clip or clips, or detent or detents, or simply with
marks so that the lens tube may be easily shifted from its position for optical focus
to that for actinic focus or vice versa, the object being to enable the lens to be
adjusted to give a sharp optical definition on the receiving screen and afterwards be
shifted the exact amount to bring it into focal adjustment for a sharp actinic or
chemical image.
Dated this 16th day of November 1891
HERBERT & Co.,
. Agents to Applicant.
COMPLETE SPECIFICATION.
Improvements relating to the Adjustment of Photographic Lenses.
I GERHARD RODENSTOCK of the Optisch-occultisches Institut, Munich in the
Empire of Germany do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement:-
This invention relates to the adjustment. of photographic lenses and its purpose is
to allow the lens to be adjusted for the actinic or chemical focus as well as for the
visual or optical focus.
The lens tube or tube carrying the lens or combination of lenses is movable back
and forth in a socket which may be fixed when the lens tube itself does not require
optical focal adjustment or movable when the focal position, varying according to
the position of the object photographed, is adjusted by movement of the lens in the
camera front.
The movement of the lens tube in its socket aforesaid is limited by any suitable
device, such as a pin and slot, the latter plain or provided with a right angled
recess or recesses, or a spring or spring clip or clips or detent or detents, or simply
with marks so that the lens tube may be easily shifted from its position for optical
focus to that for the corresponding actinic focus or vice versa, the object being to
enable the lens to be adjusted to give a sharp optical definition on the receiving
screen and afterwards be shifted the exact amount to bring it into focal adjustment
for a sharp actinic or chemical image.
This invention is illustrated in the annexed drawing in which Fig. 1 shows the
lens tube in position in the socket a for the optical focus. The lens being placed

page_text: in this position with the pin d at the forward end of the slot c, the view or object is
focussed in the usual way. The lens is then shifted into the second position shown
in Fig. 2. with the pin d in the square recess in slot c and will then be accurately
adjusted for the actinic focus. The length of slot c is chosen in proportion to the
distance between the visual and actinic foci.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is.
A lens tube having a limited or measured free movement longitudinally equivalent
to the distance between the optical and actinic foci, for its adjustment in the manner
described.
HERBERT & Co.,
18, Buckingham Street, Strand, London, W.C., Agents to Applicant.