Year: 1888

page_text: Date of Application. 20th Apr., 1888
Complete Specification Left, 7th Jan.. 1889
Complete Specification Accepted, 12th Feb., 1889
JOHN HARMER, Photographer, Wick, Littlehampton, Sussex, do hereby declare the
nature of this invention to be as follows:-
The object of my invention is to provide a means whereby the dark slide containing
the sensitive plate may be placed in the camera and its shutter drawn ready for
exposure before the preliminary operations with the sitter, up to and including
focussing the image on the focussing screen, have been proceeded with and to provide
a means whereby the camera may be in an instant automatically rendered fit either for
the immediate exposure of the sensitive plate or for focussing or refocussing, the change
from the one condition to the other being effected by a sliding back. The motion of this
sliding back arrangement not only brings focussing screen or sensitive plate in front
of the lens at will but provides for the covering or uncovering of the lens and
focussing screen at the proper moment to prevent the light from having access to the
sensitive plate.
To carry out my invention, I add to the back frame of the camera an opaque board A.
(see drawings herewith) pierced opposite the lens with an aperture the full size of
plate used and extending to a suitable distance above or below, or to either side, as
required, to form a shield for the sensitive plate. On this shield are fixed two grooved
strips in which the fixed frame or dark-slide holder B. with focussing screen C.
attached slides. At the top of this shield is fitted a small lever or plunger D. which
passes through the board A. and when operated upon by the sliding upwards of B.
compresses the pneumatic arrangement M. which by operating in turn through the
threeway tube N. causes the usual pneumatic shutter G. in front of the lens O
to rise.
In the rebate of the frame and in front of the focussing glass C. a lid or shutter E.
is hinged to open into the camera immediately the focussing screen moves into position
for focussing.
Figs. 1. & 2. illustrate the camera in the condition for focussing. The dark-slide F.
containing sensitive plate is here shewn placed in the frame B. with its shutter H

page_text: drawn. The focussing screen C. is opposite the lens and is uncovered by its lid E.
being down, and the plunger D. being pressed through A. by B. has compressed M.
and raised G. to admit light through the lens O.
Figs. 3. and 4. show the camera with plate in position ready for exposure. Here
the plunger D. having been released from the pressure of B. has allowed the shutter G.
to cover the lens O. opposite to which the dark-slide F. has then moved. The lid E.
is up and covers the screen C. the operation of sliding the back B. downwards having
automatically rendered the camera fit for the exposure of the sensitive plate in the
dark slide F. by the hand ball P in the usual way.

page_text: I, JOHN HARMER, Photographer, Wick, Littlehampton, Sussex, 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 :-
The object of my invention is to abolish all the fidgetty operations hitherto necessary
in transforming the photographic camera from its condition for focussing the image to
that necessary for making the exposure upon the sensitive plate. These various
operations 1 include and automatically accomplish in the simple act of sliding the back
as herein described whereby the lens and focussing screen are covered or uncovered
at the proper instant without the possibility of light reaching the plate, which is already
placed in its holder whose shutter is drawn.
My invention is now commercially known as "Harmer's Sliding Camera Back."
To carry out my invention I add to the back frame of the camera, and made detach-
able or otherwise, as required, an opaque board or shield A pierced opposite the lens
with an aperture the full size of plate used and extending a suitable distance above or
below and to either side to form a shield for the sensitive plate. On this board or
shield are fixed in the direction of its greatest length two grooved strips a. a. in which
slide the feather edges of two other strips b. b. affixed to the frame or dark slide
holder B. B is in all respects similar to the shield or back frame of the usual form of
repeating back camera but has the ocussing screen fitted and affixed to form one piece;
the whole sliding together upwards or downwards on the shield A by means of the
feather edges of the strips b. b. engaging the grooves of the strips a. a.
On the upper
edge of the sliding back B is fitted a plunger D which as the back is raised compresses
the rubber ball M which is closely confined in a turned brass or wooden case m. and
whose compressed air is conveyed by means of tubing to the pneumatic shutter G.
and utilized to raise its lid and uncover the lens 0. In an inside rebate of the
frame holding the ground glass or focussing screen C and to its lower edge is
hinged a lid or shutter E to open downwards into the camera immediately the
focussing screen moves into position for focussing. Its fall at the right instant is
ensured by the projecting catches S S. on the shield A and door E respectively,
being so arranged that they cannot pass each other till the lid E is upset and
has fallen inwards; and its immediate rising, when the back B is lowered to cover
the screen C, and to exclude all light from the camera, by the strip of wood V,
the width of the space intervening between the shield A and rising back B,
fastened to and continued to the bottom of the lid E where it is rounded off to
avoid jerkiness. This strip can only pass downwards when the lid is shut quite
close. Should the sliding back be required for use with very short-focus lenses I
divide this lid E across the centre as shown in Fig. 5 and hinge either half to
the top and bottom of the rebate in the focussing screen frame on pivots, and

page_text: make them to open and close together by connecting them by means of a link in
the manner shown; the arrangements for their opening and closing being by the
engagement of the catch S with that on the shield A in the same way as when
the door E is in one piece.
The pneumatic shutter employed may be of the usual form and either placed
before the lens or behind it, that is in the camera. In the latter position it must
be adjusted to open flap downwards. These usual forms, however, require the
addition of a second bellows in their pneumatic arrangements as shown at Q.
Fig. 8, one of which by its nozzle L is connected to the hand-ball P in the
usual manner;
the other being connected to and operated by the ball M at the
top of the shield A by the plunger D on the sliding back B. With those forms
of shutters which from their construction will not admit of the addition of this
supplementary bellows the threeway tube or cut-out Fig. 9 is needed; to prevent
the compression of one ball from expending its energy in expanding the other
instead of operating the shutter.
This threeway tube as illustrated consists of the main tube K with three nozzles X.
XI, XI, two of which have screw caps W. W. and are screwed on the main
tuhe K, the tubes being continued through the caps to project as a lip on the
inside. In the main tube K is a close-fitting piston u whose ends y. y. are padded
with wads of india-rubber or greased leather to ensure air-tightness when in contact
with the projecting lips of either nozzle. Its method of use and mode of operating
is as follows-The nozzle X at right angles to the main tube K is connected to
the shutter, the others respectively to the balls M and P. When either of these
latter are compressed the piston U is forced by the air pressure to close the
passage to the opposite one, and free the passage X for the air to pass to expand
the bellows of the pneumatic shutter, and to prevent its finding its way into the
uncompressed ball, therefore, whichever ball is squeezed the other one is imme-
diately cut-out without any loss or mis-application of its compressed air.
On the back of the shield B and around the aperture through which the image
is admitted to the sensitive plate, and between the feathered strips b. b., are placed
strips of wood sufficiently thick to work light-tight to the shield A., the lower
one being cut away to receive the catch S on the shield \.
At the lower part of the shield A are screwed some wood stops to support B when
it is in its lower position and on the side a brass spring to support it when raised to its
upper one.
The manner of use of "The Sliding Camera Back" is illustrated in the three sheets
of drawings herewith which contain the following figures.
Figs. 1 and 2 illustrate the camera in the condition for focussing. The dark slide F
containing the sensitive plate is here shewn placed in the frame B with its shutter H
drawn. The focussing screen C is opposite the lens and is uncovered by its lid E
being down and the plunger D on the top of B has compressed M and raised G to
admit light through the lens O.
Fig. 3 shows the camera with plate in position ready for exposure. Here the plunger D
having withdrawn its pressure from M has permitted the shutter G to cover the lens
opposite to which the dark slide F has moved. The lid E is up and covers the screen C
the operation of sliding the back B downwards having automatically rendered the
camera fit for the exposure of the sensitive plate in the dark slide F by pressure on
the hand-ball in the usual way.
Fig. 4 shows enlarged views of the operations of the plunger D on the ball M.
Fig. 5 is an illustration of the door or lid E when divided for use with very short-
focus lenses.
Fig. 6 is a plan of the back as illustrated in figs. 1. 2 and 3.
Fig. 7. illustrates in section the door E and the method by which it is operated by
the rising and falling of the back.
Fig. 8 shows how the supplementary bellows may be added to the usual forms of the
pneumatic shutter.

page_text: Fig. 9 is an illustration of the threeway tube or cut-out whose object and manner of
use have been described.
Like letters relate to like parts in all the figures.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1st. The arrangement of the dark slide holder B and focussing screen C, joined in
one piece, to slide unenclosed on the shield A; the whole to form the back of or be
added to the usual forms of photographic cameras, to which it is applied, either
detachable or as a fixture, as particular cases require, and its use, substantially as, and
for the purposes, described.
2nd. The combination with the abovo of the pneumatic ball and its close fitting
case M and the plunger D, their mutual interaction and method of operating by
the sliding of the back substantially as, and for the purpose, described.
3rd. The door E, divided or otherwise with its fittings, and its automatic operation
by the sliding of the back.
4th. The addition of the second or supplementary bellows to the usual form of
pneumatic shutter for use with the camera back substantially as described.
5th. The threeway tube or cut-out and its use for the purpose substantially as
described.
6th. The combination of the whole of the above for the purpose substantially as
described.
D
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