Improvements in and in connection with Photographic Cameras.
Year: 1892

page_text: Date of Application, 26th Oct., 1892
Complete Specification Left, 26th July, 1893-Accepted, 2nd Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in and in connection with Photographic Cameras.
I, EDMUND HAWTHORN MICKLEWOOD, of 5 St. Michaels Terrace, Plymouth,
in the County of Devon, Engineer, do hereby declare the nature of this invention
to be as follows:-
My invention relates to a means of exposing sensitive plates or films in a photo-
graphic camera so as to give a due ratio or balance of exposure to all parts, and
refers to the invention described in the Specification of my Patent No. 9042, dated
28th May 1891; in that invention I effected the desired result by means of a rising
and falling shutter in combination with a dark chamber between the lens and the
shutter; now simplify the mechanical details and produce the same result by
having the shutter, still in combination with the said dark chamber, but with a
motion in one direction only, under which condition the result may be attained in
either of the following methods.
1. The opening in the shutter, which by passing vertically across front of dark
chamber effects the exposure, may move at a uniform speed, but the actuating
mechanism to be so connected with an iris diaphragm on the lens, that the several
parts of the sensitive surface shall receive the desired variation of exposure by the
expansion or contraction of the diaphragmatic opening.
2. The said opening in the shutter is so controlled by suitable mechanism that
its motion across the exposing aperture shall be one of uniformly accelerated or
retarded speed according as its passage is in an upward or downward direction.
The above result may be attained or enhanced by combining with the actuating
mechanism a brake which comes into action during the slow part of the motion only
or allows a graduated speed by a graduated degree of friction.
3. The slot in the shutter may pass in front of opening of chamber in a horizontal
direction at a uniform speed and the graduation of exposure may be attained by
having the slot of a V shape whereby the wider part exposes the foreground and
the narrower part the sky.
It will be apparent from the optical considerations involved that the dark
chamber may be formed before or behind the lens, the motion of the shutter being
reversed in the latter case on account of the crossing of the rays of light after
passing through the lens.
In every case the combination of the dark chamber with the moving shutter at
opposite end thereof to the lens is essential for reasons fully set forth in the
Specification of my Patent No. 9042 of 1891.
Dated this 26th day of October 1892.
E. H. MICKLEWOOD.
Brewer & Son,
33, Chancery Lane, London.
COMPLETE SPECIFICATION.
Improvements in and in connection with Photographic Cameras.
I, EDMUND HAWTHORN MICKLEWOOD of 5 St. Michaels Terrace, Plymouth,
in the County of Devon, 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 :-
My invention relates to a means of exposing sensitive plates or films in a
photographic camera so as to give a due ratio or balance of exposure to all

page_text: parts, and refers to the invention described in the Specification of my Patent
No. 9042 dated 28 May 1891; in that invention I effected the desired result by
means of a rising and falling shutter in combination with a dark chamber
situated between the lens and the shutter; now simplify the construction and
produce the same result by having the shutter, still in combination with the
aforesaid dark chamber, but with a motion in one direction only, under which
condition the result may be attained by either of the following means:
(1) The opening in the shutter, which, by passing vertically across front of dark
chamber effects the exposure, may move at a uniform speed but the actuating
mechanism to be so connected with an iris diaphragm on the lens that the
several parts of the sensitive surface shall receive the desired variation of
exposure by the expansion or contraction of the diaphragmatic opening.
would point out that the contraction of the diaphragmatic opening in a lens
with iris diaphragm would in its effect be equivalent to a higher speed of shutter,
hence considerable variation could be effected in this manner in the ratio of
exposure given to the different parts or sections of the plate while the. shutter
itself moved at a uniform speed. Any suitable simple mechanical means may
be employed, by which the mechanism actuating the shutter shall be made also
to control the opening given by the iris diaphragm and as many mechanical
expedients for effecting the combined motions will readily suggest themselves to
those acquainted with such devices I do not consider it necessary to further
describe same.
(2) In some cases the said opening in the shutter is so controlled by suitable
mechanism that its motion across the exposing aperture shall be one of uniformly
accelerated or retarded speed according as its passage is in an upward or down-
ward direction. This result may be attained or enhanced by combining with
the actuating mechanism a brake which comes into action during the slow part
of the motion only, or allows a graduated speed by a graduated degree of
friction.
With reference to this second arrangement 1 illustrate in the accompanying
drawing two means by which that end may be attained in a simple and efficient
manuer.
Referring to Figure 1 which is a diagram vertical section; BS represents a
blind shutter, which for setting is wound on to the roller R2 and in setting off or
doing its work of exposure is rewound on to the roller R. The motive power in
this instance may be a coiled spiral spring inside the roller R. The lower
roller R2 is provided outside the containing case, as shewn in the diagram Figure 2
in part end view, with a pinion P, driving a wheel W and an eccentric or cam E
which in its revolution is controlled by a brake B in such a
during the earlier part of its motion the brake B regulates its speed but having
attained its maximum lift it is free from further control and the spring of the
shutter being freed of control the completion of the movement of the shutter is
much more rapid than before.
manner that
The slower movement coincides with the exposure of the foreground while the
more rapid one coincides with that of the sky. It will therefore be evident that
by.a suitable proportion between the pinion and wheel and the necessary shape
being given to the eccentric or cam any given portion of the movement of the
shutter BS may be slow and the remainder accelerated.
A very definite and simple method of transmitting a uniformly accelerated
motion to the shutter may be given by the method as illustrated in diagram,
Fig. 3, in which R₁ and R represent two rollers on which the blind BS is alter-
nately wound and unwound. In this case the roller R' is driven by a toothed
ellipse indicated at E' which in its turn is driven by the equal and similar toothed
ellipse E' which latter is or may be actuated by a coiled spring. As two similar
ellipses movable about opposite foci, will, when suitably geared, drive one another at
a constantly waxing and waning speed, it follows that if the elliptical wheel E³ be
connected to the axis of the roller R and driven by the ellipse E¹ in such a

page_text: manner as to start with the slowest motion and so gradually increase until the
revolution is finished at the highest speed, it follows that the flexible blind BS
connected to and wound up by the roller R₁ will have a steadily increasing
rate of rise during its passage from R² to R' and this ratio of speed be the
same when E is driven at a uniform speed, whether that speed is a high or a low
speed, hence the rate of motion of E¹ may be controlled by a friction or other
brake or the brake may act during the early portion of its movement only so as to
still further enhance the difference between the carlier and latter part of the motion
of the shutter.
(3) The slot in the shutter may be caused to pass in front of opening of the
dark chamber in a horizontal direction at a uniform speed and the graduation of
exposure may be attained by having the slot of a V shape whereby the wider part
exposes the foreground and the narrower part the sky, and from its shape allows a
greater number of light rays to pass from the lower part of view to the sensitive
plate than from the higher or sky portion.
In every case for reasons fully set forth in the Specification of my Patent
No. 9042 of 1891, the interposition of the dark chamber between the moving
shutter and the lens is requisite to attain the desired result.
It will be apparent that the dark chamber may be formed before or behind the
lens the motion of the shutter being reversed in the latter case on account of the
crossing of the rays of light after passing through the lens.
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 I do not
claim the mere mechanical construction which can be varied within wide limits, but
what I do claim is :
1. In photographic cameras the combination with a shutter having a motion
across the face of a dark chamber interposed between the shutter and the lens, of
a connection between the said shutter and the diaphragm or working aperture of
the lens whereby the latter is controlled simultaneously with the movement of the
shutter, as set forth.
2. In photographic cameras, the combination with a shutter having a graduated
motion, of a dark chamber interposed between the said shutter and the lens, as set
forth.
3. In photographic cameras the combination with a shutter, having uniform
motion but an irregular shaped opening, by which, in combination with a
dark chamber interposed between the said shutter and lens, a due ratio of
exposure is given to the several parts of the sensitive plate substantially as
set forth.
4. The general arrangement and combination of parts composing my improve-
ments in and connected with photographic cameras, substantially as and for the
purposes herein before described.
Dated this 26th day of Tul 1002
BREWER & SON,
London and Leeds, Agents for Applicant.
BREWER & SON,
London and Leeds, Agents for Applicant.