Improvements in Photographic Cameras.
Year: 1896

page_text: Date of Application, 25th
Aug., 1906
דים
Complete Specification Left, 25th May, 1897-Accepted, 10th July, 1897.
Complete Specification Left, 25th May, 1897-Accepted, 10th July, 1897.
PROVISIONAL SPECIFICATION.
Improvements in Photographic Cameras.
I, LODEWYK JAN RUTGER HOLST of 259, Heerengracht, Amsterdam in the
Kingdom of Holland, Engineer, do hereby declare the nature of this invention to
be as follows:-
This invention relates to a photographic reflecting camera, which, for the
purpose of wholesale manufacture is so arranged that it is applicable without
further treatment for all objectives used in commerce with given sizes of plates.
If the
The focal distances of the various systems of objectives for the same sizes of
plates differ in fact within wide limits from one another; for instance, for plates
of 9 x 12 centimetres, objectives are used of 12 to 18 centimetres focal distance,
and in the existing form of construction of reflecting cameras it is impossible to use
the same camera both for an objective with a long and an objective with a short
focal distance. If the camera be arranged for an objective with a short focal
istance, an objective with a longer focal distance can only be used with a
considerable loss of light both for the plate and for the focussing screen.
camera, on the other hand, be so constructed that an objective with a longer focal
distance may be used without loss of light, then objectives with a shorter focal
distance cannot be used at all. In reflecting cameras, the distance of the rear face
of the objective board from the plate gives the measurement for the length of
mirror to be employed, so that in objectives with a short focal distance only a short
mirror or reflector can be used. If then such a camera be provided with an
objective of long focal distance, the opening exposed by turning up or raising the
nirror will not be large enough to allow the cone of light from the objective to
pass through unimpededly, a considerable part of the rays is caught or absorbed by
the under part of the partition which serves as a support for the mirror and is thus
rendered ineffective for the plate. Moreover the picture reflected from the mirror
on to the focussing screen is also weaker in light than it should be.
In order to avoid these drawbacks, the mirror by the present invention is formed
in two parts, one of which is adapted to be turned upwards and the other down
wards, so that an opening is exposed which is large enough to allow the light cone
of an objective with even a long focal distance to pass through unimpededly. By
this arrangement the advantage is also attained that the two parts may be so
arranged as to equipoise one another, so that only a minimum pressure is necessary
for lifting the mirror.
The mirror or reflector consists of two parts of which the one is pivotted above
and the other below. An arm is attached at the back to the upper part of the
mirror and is connected by means of a link with the lower part of the mirror in!
such a way that if the upper part be turned upwards the lower part will turn to a
corresponding extent downwards. The operation of the mirror is effected by a
push button which engages the end of a fever whose other end engages below an
arm on the upper part of the mirror so that, on the push button being pressed
down the upper part of the mirror is raised, and closes the light passage of the
focussing screen from below,

page_text: The objective board firmly connected with a slide board is adjusted or moved
longitudinally of the camera by means of a pinion which engages in a rack
mounted on the slide board.
If the lower part were fixed, a part of the plate upward from the lower edge
would remain quite unexposed, whilst the light could only act partially on the
plate for some distance above. If the objective be pushed further forward for the
purpose of adjusting it to nearer objects, the unlighted or only partially exposed
parts of the plate become correspondingly greater. For portrait objectives with
the longest focal distance which can be used in the camera the limits of said parts
are much greater. In the latter case, therefore, about one fifth of the plate
remains quite unexposed and only about two-thirds of the plate would receive full
light. In such arrangement of the mirror all rays of the light cone from the
objective are actually thrown upwards by the mirror on to the focussing screen,
so that the picture as seen on the screen appears in full strength of light.
If desired, the mirror coating may be omitted from the lower part of the mirror
or reflector, so that no rays will be reflected on to the focussing soreen from this
part. The picture appearing thereon then appears somewhat weaker in light,
whilst the sensitive plate receives the full cone of rays as the lower part of the
mirror is turned down for the exposure.
As the length of the racks necessary for the adjustment of the objective board
must naturally be limited, I have designed an arrangement for objectives with
longer focal distances to afford as large a movement of adjustment as possible by
the pinion spindle being adjustable to variable distances from the front wall of the
camera. For this object, in the wall of the camera four holes are provided and
covered by means of a plate with two sockets engaging say in the second and fourth
holes. The pinion spindle passes through one of the sockets, whilst the other
socket is closed by means of a screw. On the opposite wall of the box a bar is
provided with recesses corresponding to the said holes to receive the other end of
the pinion spindle. By using the second or fourth socket and also by turning or
reversing the plate the pinion spindle may be placed in any one of the four holes.
On the outermost end of the spindle a button or milled head is arranged by means
of which the spindle may be rotated.
Dated this 24th day of August 1896.
WM. P. THOMPSON & CO.,
Of 6 Lord Street, Liverpool, Agents for the Applicant.
Improvements in Photographic Cameras.
I, LODEWYK JAN RUTGER HOLST of 259 Heerengracht, Amsterdam in the
Kingdom of Holland, Engineer, 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 a photographic reflecting camera, which, for the
purpose of wholesale manufacture, is so arranged that it is applicable without
further treatment for all objectives used in commerce with given sizes of plates.
The focal distances of the various systems of objectives for the same sizes of
plates differ in fact within wide limits from one another; for instance, for plate's
of 9 x 12 centimetres, objectives are used of 12 to 18 centimetres focal distance,
and in the existing form of construction of reflecting cameras it is impossible to
use the same camera both for an objective with a long and an objective with a

page_text: short focal distance. If the camera be arranged for an objective with a short foenl
distance, an objective with a longer focal distance can only ho used with a
considerable loss of light, both for the plate and for the focussing screen.
If the
camera, on the other hand, be so constructed that an objective with a longer focal
distance may be used without loss of light, then objectives with a shorter focal
distance cannot be used at all. In reflooting cameras, the distance of the rear face
of the objective board from the plate gives the measurement for the length of
mirror to be employed, so that in objectives with a short focal distance only a
short mirror or reflector can be used. If then such a camera be provided with an
objective of long focal distance, the opening exposed by turning up or raising the
mirror will not be large enough to allow the cone of light from the objective to
pass through unimpededly, a considerable part of the rays is caught or absorbed
by the under part of the partition which serves as a support for the mirror and is
thus rendered ineffective for the plate. Moreover the picture reflected from the
mirror on to the focussing screen is also weaker in tight than it should be.
In order to avoid these drawbacks, the mirror by the present invention is formed
in two parts, one of which is adapted to be turned upwards and the other down-
wards, so that an opening is exposed which is large enough to allow the light cone
of an objective with even a long focal distance to pass through unimpededly. By
this arrangement the advantage is also attained that the two parts may be so
arranged as to equipoise one another, so that only a minimum pressure is necessary
for lifting the mirror.
Such a camera is shown in the accompanying drawings, in which,
Figure 1 is a vertical longitudinal section, whilst
Figures 2 and 3 are details of the adjusting mechanism in horizontal section and
side elevation respectively.
The mirror or reflector consists of two parts Hand G of which the former is
pivoted above at the point U and the latter below at the point 0. An arm K is
attached at the back to the upper part H of the mirror and is connected by means
of a link L with the lower part G of the mirror in such a way that if the upper part
bo turned upwards the lower part will turn to a corresponding extent downwards
as shown in dotted lines. The operation of the mirror is effected by a push button N
which engages the end of the lever M whose other end engages below an arm I
on the upper part of the mirror II, so that, on the push button N being pressed
down the upper part 1 of the mirror is raised and closes the light passage T of
the focussing screen from below.
The objective board A firmly connected with a slide board B is adjusted or
moved longitudinally of the camera by means of a pinion D which engages in a
rack C mounted on the slide board B.
The objective board is shown in Figure 1, in full lines in position for an
objective with a short focal distance, whilst the position for an objectivo with a
onger focal distance is shown in dotted lines. In order to show what essential
nfluence the lower movable part of the mirror has on the lighting or exposure
of the plate the rays from the objective are indicated by lines -
TIL
ho position of the objective shown in the drawing, if the part G were fixed, a part
of the plate up to P and P from the lower edge % of the plate would remain quite
inexposed whilst the light could only act partially on the plate from P and P up
o Q and Q. If the objective be pushed further forward for the purpose of
djusting it to nearer objects, the unlighted or only partially exposed parts of the
late become correspondingly greater. For portrait objectives with the longest
ocal distance which can be used in the camera shown on the drawing, R and R
ndicate the limits of said parts. In the latter case therefore about one-fifth of the
late remains quite unexposed and only about two-thirds of the plate would
eceive full light. In such arrangement of the mirror all rays of the light cone
rom the objective are actually thrown upwards by the mirror on to the focussing
creen, S, so that the picture as seen on the screen appears in full strength of light.
If desired, the mirror coating may be omitted from the lower part G of the mirror

page_text: or reflector, so that no rays will be reflected on to the focussing soreen S from this
part. The picture appearing thereon then appears somewhat weaker in light,
whilst the sensitive plate receives the full cone of rays as the lower part G of the
mirror is turned down for the exposure.
As the length of the racks C necessary for the adjustment of the objective board
must naturally be limited, I have designed an arrangement for objectives with
longer focal distances to afford as large a movement of adjustment as possible by
the pinion spindle D being adjustable to variable distances from the front wall of
the camera. For this object, in the wall of the camera shown as an example in
the drawing, four holes R R R and R³ are provided and covered by means of a
plate F with two sockets O or P engaging in the second and fourth holes. The
pinion spindle D passes through one of the sockets, whilst the other socket is closed
by means of a screw Q. On the opposite wall of the box, a bar V is provided with
recesses corresponding to the said holes R to receive the other end of the pinion
spindle. By using the socket O or the socket P and also by turning or reversing
the plate the pinion spindle may be placed in any one of the four
holes R R R or R³. On the outermost end of the spindle a bottom or milled
head E is arranged by means of which the spindle may be rotated.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. The improvement in photographic reflecting cameras, which consists in
forming the mirror or mirror support in two parts (II and G), the first of which is
adapted to be turned upwards and the second downwards with the object of
enabling the camera to be used both for objectives with short and objectives with
long focal distances substantially as described.
2. In a camera of the kind described, the means for adjusting the pinion
spindle (D) of the racking device for operating the objective board, whereby,
according to requirements, said spindle may be arranged in one of several support
openings (R R R and R³), and an adjustment of the objective board be effected
within wide limits with a comparatively short length of rack, substantially as
described.
WM. P. THOMPSON & CO.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.