Improvements in Photographic Cameras.
Year: 1891

page_text: Date of Application, 12th Jan., 1891-Accepted, 14th Feb., 1891
[Communicated from abroad by THOMAS ARDERN, Camera Maker, of Melbourne,
in the Colony of Victoria.]
Improvements in Photographic Cameras.
I, SAMUEL CALVERT, of 36, Great Ormond Street, in the County of London,
Artist, 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 construction and arrangement of photographic
cameras of field glass form in such a manner as to afford great convenience in
focussing, in working the shutters in accommodating a number of plates and
exchanging exposed for fresh plates, as will be described with reference to the
accompanying drawings.
Fig. 1 is a longitudinal section partly in elevation of an instrument according to
this invention,
Fig. 2 is a section on X X shewing the shutter mechanism.
The hinder part of the instrument is divided by a partition a into two chambers A
for exposing the foremost of the plates in it (of which there are a number piled
together to fill the chamber) and B for focussing and for effecting the transfer of
one of the plates from the front to the rear of the pile in A. Each of the plates
or films is suitably sheathed.
In the hind cover C, which can be removed like a lid, are two apertures axial
with the chambers A and B respectively. The one aperture has within it a sliding
tube having a hole through its outer end fitted with an orange or ruby coloured
glass h so that the operator can see through it to read the number or mark on the
sheath of the hindmost plate, but that the light entering cannot actinically act on
the plates in the compartment. The front part of the tube has two parts i which
can project through slots in the front plate. On applying the finger to push in the
glass in opposition to a spring contained in the tube f the whole pile of plates can
be pushed forwards. The aperture axial with B is fitted with a sliding eye piece k
containing an objective lens. This eye piece adjusted to suit the operator's vision
enables him to keep his eye close to the camera while focussing, and so to dispense
with the hood, shade or guard usually required to exclude light. The partition a
has at each end an opening wide enough for passage of a plate, and a door m is
hinged so that it can fold against the partition a or against the inner face of the
lid C. When it is desired to transfer the foremost, 1, of the plates in A to take
the place of the hindmost, the instrument is first canted so that the door m lies
across the aperture of the eye piece & preventing access of light, then the canting is
such that the plate 1 slides into B and falls on the door m, the tube is then pushed
in so as to advance the whole pile of plates in A, the camera being now canted
downwards on the left, the plate 1 slides from off the door m partly into the space
in A behind the pile of plates, and when on relieving the pressure on the pro-
jections are withdrawn by the spring, the plate 1 slides completely into the
hindmost space.
The door m being now turned forward so as to cover the openings at the end of a
and prevent access of light, the plate 2 is ready for exposure in its turn.
The shallow shutter box contains a pair of diaphragm sliding shutters p p¹ for the
opening to the chamber A and a sliding shutter for the opening to the chamber B.
Two wheels D and E gear with one another. The wheel D is on a tubular axis
which projects forwards through a spring box in which it is surrounded by an
adjustable coiled spring F, and its front end has the lens holder G fixed on it.
The wheel D has projecting back from it two eccentric studs r which work in
transverse slots of the shutters p and p' respectively.

page_text: g.
The wheel E has a crank pin linked by a connecting rod u to the shutter
The operator taking hold of the lens holder G which he covers with his palm to
exclude light, turns it partly round thereby winding up the spring F, first with-
drawing the shutters p pf and partly withdrawing the shutter q, and then closing pp
and fully opening g
The wheel E is thus turned so far that the point w of a spring trigger pin enters
a hole in the face of the wheel E thus holding the shutters in the positions to which
they had been moved with the spring F under strain. The parts are so arranged
that the turning of G about one quarter round opens the shutters ppl but only half
opens q, another quarter turn closing p p but quite opening 9 in which positions the
shutters are held while the operator can focus. The trigger pin extends from w
through a tube within the focussing screw surrounded by a helical spring and
terminates in a trigger J. On the trigger pin is a lateral stud z which bears against
the sloping face of the screw sleeve H.
When it is desired to release the shutters the trigger J is turned partly round
and its stud z travelling along the slope of H retracts the pin w leaving the wheel E
free. Thereupon the spring F causes a rapid movement of the wheels D and E,
first opening and then closing the shutters ppl and closing the shutter q.
The shutter box and lens holders are mounted as usual on tubes which, for
adjusting focus, can be slid forwards or backwards in the usual way by turning the
nut I.
The arrangement of shutters p p in combination with a rotatable lens holder such
as G and spring F, is obviously applicable to cameras generally, whether there be a
second shutter q connected therewith or not. When there is no such second
shutter, the gearing wheels D and E and the crank and connecting rod of E are
dispensed with, and the trigger or other detent for holding the shutters closed is
applied to any convenient part of the rotatable lens holder. The spring F may
be more or less wound by turning the barrel enclosing it relatively to the lens
holder, and securing it by a pawl, and thus the velocity of the closing movement
of the shutters can be regulated and consequently the period of exposure.
Figs. 3 and 4 are respectively longitudinal and transverse sections of a modified
construction of the exposing and focussing compartments and of the means of
changing the position of the plates. In the exposing chamber A the plates are
piled as before, a pile of them having been introduced on unscrewing the end
cover A and pushing them in over spring latches u which hold the pile in position
leaving the last plate 13 ready to be pushed in by means of the spring pusher f.
To the end cover A¹ is fixed a cylinder f¹ which at one part of its circumference
has an opening f at each end wide enough for passage of a plate.
To the cylinder 1 is fixed a toothed segment which through an intermediate
pinion gears with a wheel m axial with the compartment B. This wheel works a
pair of shutters p³ p³ in the same manner as the wheel D described in reference to
Figs. 1 and 2.
By means of the end cover A¹ the operator can turn the cylinder f¹ partly
round so as to present the openings f towards B at the same time by the partial
rotation of m the shutters p p are closed so as to exclude light. The foremost
plate 1 can then by canting the instrument be caused to slide from the compart-
ment A into B, then, the last plate 13 in A being pushed beyond the latches n,
the plate 1 can be slid out of B into the place previously occupied by the plate 13;
and, the cylinder f¹ being now turned back so as to remove its openings from facing
the openings into the compartment B, the shutters p² p³ are opened allowing the
operator to focus for exposure of plate 2 which is now foremost.
-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
-
1. A photographic camera of field glass form having in front a pair of lens
olders with shutter box attached thereto and their sliding tubes adjustable for

page_text: focussing, and having in rear two compartments the one compartment arranged to
hold a pile of sheathed plates or films and advance them for exposure in succession,
the other compartment arranged for focussing and for transferring each plate in
succession from the front to the rear of the pile, substantially as described,
2. In combination with the two compartments above referred to a spring push
with non actinic glass for the one and a hinged door for the other arranged and
operating for transferring a plate from front to rear of the pile, substantially as
described.
3. The modified construction and arrangements of the rear compartments and
their appliances for transferring plates, substantially as described with reference to
Figs. 3 and 4.
4. In combination with the focussing compartment, an adjustable eye piece with
objective lens, substantially as and for the purpose set forth.
5. In a photographic camera, the combination of a rotatable lens holder and
coiled spring with a pair of sliding shutters having transverse slots engaged with
eccentric studs on the lens holder, so that, on the release of a trigger or detent,
the lens holder is caused by the spring to make a partial revolution opening and
then closing the shutters, substantially as described.
6. In a field glass camera, in combination with the shutter apparatus referred to
in the preceding claim, a sliding shutter for the focussing aperture moved by crank
and gearing from the rotatable lens holder, and a trigger with its pin and spring
arranged within the tubular focussing screw, substantially as described.
Dated this 12th day of January 1891.
ABEL & IMRAY,
Agents for the Applicant.