Compur Shutters Service Manuals

Compur Shutters

Compur and Compur Rapid shutters represent the most advanced

commercially available interlens shutters and, apart from a recent
development marketed in the United States, have for a number of
years formed the mainstay of many of the better-class miniature
cameras which for one reason or another utilize an interlens shutter.

One of the advantages which this type of shutter offered to the

camera manufacturer was its ready availability in a complete unit

form. In many cases the manufacturers would buy suitable shutters
for the lenses they proposed to use and fit them to an otherwise simple

form of focusing mount. In this way they did not have to design a
focal plane shutter which, with the interlock mechanism, forces a

completely new approach from the designer.

Another strong argument for the adoption of the interlens
shutter was its very moderate price. The manufacture of Compur and
Compur Rapid shutters was a monopoly of the Deckel factory in
Germany. The output was sufficiently high to warrant and pay for

highly specialized machinery and since the manufacturer was assured
of a steady and expanding market he could well afford to keep the
price down, thus making it exceedingly unprofitable for anyone to
venture into competition. Germany's virtual stranglehold on shutter
production was helped by the possession of all relevant patents. The
necessity of circumventing these was primarily responsible for the
Kodak Supermatic design which made the United States in some
small way independent of German production. Now, after the

customary 15 years, the patents have become void and at the time
of writing, some firms are tooling up for the manufacture of Compur­type shutters.

In the Compur and Compur Rapid shutters, one movement is

necessary to put the various springs in tension and another, a

118

MINIATURE CAMERA CONSTRUCTION

separate one, to release the mechanism whereby the actual opening
action takes place. Apart from this dual action there are three
distinct operations which are performed by a single shutter. First
is the opening and closing of blades. Second is the action which
controls the length of time the blades are in the open position,

Opening and closing take the same time but are separated by vary-

ing delay intervals to achieve the required exposure. Third is the

ingenious mechanism to provide time and bulb shutter settings. The

opening and delaying mechanisms are then set aside and a new

system of lovers performs the action.

Apart from the timing mechanism, shutters of this type carry the
diaphragm mounting and set the lens glasses at the correct separation.
It required very considerable ingenuity by the designer to house all
these elements in the narrow annulus,

The blades of both the Compur and the Compur Rapid shutter
are made of very thin steel foil between 0.002 and 0.003 in thick, and

are pivoted as near to the centre of mass as possible (particularly in
the case of the Compur Rapid). The blades are moved by a ring
engaging pins or by the pins on the blade engaging recesses in the
ring. Both of these are close to the centre of rotation so that a very
small circular movement of the ring suffices to open the blades to
the full lens aperture. The angle through which the ring has to be
rotated

is

usually less

than

five

degrees.

The

blades

and the

ring

which moves them are shown in Figs. 4.15 to 4.18. The ring which

moves the blades will be referred to as the actuating ring. All

119

MINIATURE AND PRECISION CAMERAS

actions of the shutter mechanisms are applied to it. The ring has
usually two pins which can be pushed or pulled and force it to rotate.

Normally the actuating ring is in. a position where the blades are
closed. This is assured by the square lever engaging out of the pins
and keeping the blades closed by the action of its spring (Fig. 4.19).
It will be seen, from Fig. 4-19 that to open the blades one has to lift

the arm of the square lever.

We shall now describe the mechanism responsible for opening and

closing action performed on the square lever. The piece of mechanism

performing the action is the operating pawl which because of its
shape is commonly known as the bird pawl (Fig. 4,20), This is
mounted on the setting ring and lifts the square lever by its " beat "
which is shaped to provide the smooth opening action. To do so
the operating pawl must approach the square- lever from the right
(Fig. 4.21). The approach and withdrawal of the operating pawl are
arranged by pivoting it in the middle so iliac it can dip its " beak"
and raise its "tail" or vice versa according to the function it has
to perform.

The movement towards and away from the square lever is forced
on it by the setting ring. This ring is tenstioned and made ready for
action when the Compur shutter is set. The setting action moves the
setting ring clockwise, taking the Operating pawl away from the
square lever. It must not on any account open the blades then, so the
tail of the operating pawl is raised by the upper section of the D­shaped recess (Fig.

4.22).

Thus

the

beak

of the

operating

pawl

dips
and passes the bell crank lever without opening the blades as the tail
of it enter from the upper portion of the D groove. The same action
tensions the spring of the setting ring and towards the end of it the
Setting ring is caught by the release catch (Fig. 4.23).

The shutter is now " set " and pressure on the release lever will be
necessary to let the setting ring slip back and the operating pawl
approach against the bell crank lever. The natural position of the
operating pawl is with its beak up ; a small spring tensions it this

way. So when the clockwise movement finishes, its tail travels along

the curved portion of the D groove and finally rests on the bottom of

it. When the setting ring is released the tail of the operating pawl is
held firmly by the straight portion of the D groove. It thus rides to
the left, its beak stoutly raised, and on coming to the square lever

raises it, thus opening the blades. The blades gradually open as the

square lever rides over the head of the operating pawl and then

close as it comes, down on the other side.

Fig. 4.24 shows the do delay mechanism. The starting point here is

the

quadrant

gear

which

has to be

pushed away

for the

ring

to

slip

past it. The amount by which the quadrant gear gets into the way of

120

the setting ring is determined by the cam ring which is moved on
selecting the particular shutter speed. The quadrant gear is always
tensioned

cam ring permits. It is connected to the gear train which finally

terminates in a pallet wheel. At this moment the tail of the operating
pawl finishes riding the straight section of the D groove and the pawl
nicks up its head, releasing the square lever completely ; the blades
then close fully,

To the control of Compur shutter speeds there is first the full,
undisturbed operation by the delay mechanism where the tension of
single or double. springs on the selling ring causes the fast traverse
of the ring and performs the opening and closing action described.

against

the cam

ring

so it

will

come

out

completely

if the

121

MINATURE AND PRECISION CAMERAS

Secondly, the movement of the selling ring is impeded by the train
of gears and a pallet. A pallet is in some respects similar in action to
the escapement of a watch but is more robustly constructed to with­stand the sudden forces released into it by the operating spring.

We have seen how the closing action of the blades takes place

gradually and is accurately determined by the shape of the head of

the operating pawl and also by the moment when the tail of the

operating pawl can flick up the D-shaped recess. The delaying action
takes place before closing begins and the effect is plotted in Fig. 4.25.

We shall now have to divide operations according to whether Compur

or Compur Rapid shutters are being considered. This is best done by

the following table :

122

The

shape
been determined by the manufacturers after much research. It is
therefore fatal to the shutter to have this cam filed away, as happens
when eager amateurs decide to " improve " on the original design.
The approximate shape of the cam ring is shown in Fig, 4.26.

The bulb setting action of Compur shatters was designed for use

with cameras having automatic film winding devices and shutter

setting mechanisms. Unlike the modern types of Compur shutters.
it was necessary to cock the shutter setting ring for the B movement.

Referring to Fig. 4.27, catch pawl G is brought into play by (he
notch
when the shutter is set on. B, and the shutter release levers allowing
it to interrupt the action of the setting ring.

moves toward the setting ring and the catch F engages in a projec­tion in the suiting ring., arresting its action just as the shutter blades

have reached the fully open position.
tension returns pawl G and permits the setting ring to travel on its

way and thus close the shutter blade. Normally this lever is pushed
out of reach of the setting ring by the speed selection ring. On B

on the

Assuming the shutter is set, upon depressing the release the pawl

When pressure is removed from the release lever, the spring

of the cam on the cam ring is

speed

selection ring freeing

the

very

important

movement

of

this pawl

and has

settings however, the speed selection ring allows this lever to come
into the recess cut in the ring (Fig. 4.28).

123

The blades actuating ring has to be moved by another arrange-

ment consisting of the lever E (Fig. 4. 29} pushing one of the pins on

it. This lever can be pushed against the blades actuating ring by
another lever which we shall term C, Lever C is normally held a way
from E by the speed selection ring pressing on the lever G, but on the
bulb

position

arm E. It is directly connected with the shutter release lever (Fig,

4.30). When this is pressed lever H pushes arm B which moves
against the blades actuating ring and opens them. On letting the

release free the arm E comes hack, and lets the blades close.

Compur Rapid Fully Synchronized Shutter

In the latest development of the Compur shutter the Compur

Rapid seems to be the only design coming out in quantity production.

This shutter has both the X and the M synchronized arrangements
(see page 125). It differs from the model described above by having
an additional escapement mechanism operated by a separate

quadrant wheel. This mechanism terminates with a final gear having
a cam which actuates a lever. The lever in turn closes one electrical
contact. Thus the necessary accuracy of the small delay in the M-

setting is produced by the mechanical magnification of the move-

ment of the release lever accompanied by the controlled timing by

the pallet and the pallet wheel. The X delay is performed by the
linking of the blades actuating ring movement via the angle lever 10
the contact spring. Thus the contact is closed when the blades arc
in the fully open, position. The time setting is eliminated and a new

bulb setting mechanism is used,

the

recess

in the ring

allows

it to

come

nearer

to the

124

MINATURE CAMERA CONSTRUCTION

All modern shutters lend to dispense with the separate time and
bulb settings and provide a bulb setting only, The time setting can
still

be

obtained

by the

body

release

lock

which

is a

part

of the

camera
rather than of the shutter. The advantage lies in clearing some space
in the shutter annulus which can be occupied by the synchronizing
delay system .

Furthermore, as most modern cameras employ a combined shutter
winding and film transport mechanism, it is necessary to forgo any
shutter action which does not rely on the normal mode of shutter
operation—the rotation of the setting ring.

In the bulb setting of the Compur Rapid, a lever is arranged to
arrest the movement of the setting ring in the position where the
blades are fully open. This lever is brought into operation under
setting B only when, the cam ring allows it to move. When the

release lever is pressed, the notch on the arm of the release lever

moves behind the hack of the B lever and supports it in keeping the
setting ring stationary all the " open " position by the blades. The
removal of pressure from the release lever allows the B lever to be
pushed buck by the rotation of the setting ring, thus permitting the

complete rotation of the actuating ring (Fig- 4.31),

When the release lever is pressed it rotates a connecting link A

(Fig. 4.32), Against the arm of this lever rests the arm of the

synchronizer quadrant gear lever. This quadrant gear lever is ten­sioned so that it will rotate clockwise (Fig. 4.33) and once the

link A is rotated by the action of the release lever it can do so.

125

MINIATURE AND PRECISION CAMERAS

Three things happen as the result of the rotation of the quadrant

gear lever. After the flash contacts are closed, the escapement

mechanism is. brought into action, providing the delay, and at the
appropriate moment the setting ring is released, bringing the blades
into action. The escapement mechanism consists of a pallet wheel

driven by the small gear, connected via gears to the- quadrant gear

lever. On one of these gears a cam strikes the contact closing arm,
the other arm of which bends the contact spring and makes it touch

the " live " contact terminal (Fig. 4.34).

The third action (that of releasing the sotting ring) is performed by

the synchronizer quadrant gear lever and the setting
ring release lever. The projection on the quadrant
lever arm strikes the end of the setting ring lever,
the other arm of which releases the setting ring,

The timing of these actions is such that approx­imately 17 millisec elapse between the closing of
the contact points and the opening of the shutter
blades, Thus the setting ring has to be released a

few milliseconds earlier. The timing sequence runs as follows :

(1) Pressing of the release lever by the photographer.
(2) Closing of contact points.
(3) Releasing the setting lever thus actuating shutter mechanism

proper.

The setting X of the shutter delay makes the contacts close at the
moment when the shutter is fully open. The contact closing arm is
moved by the angle lever which engages the curved end of it and
pulls

down,

to

dose

the gap

(Fig.

4-35).

Prontor II and Klio shutters

The Prontor II and Klio shutter represent the same level of
mechanical achievement as the Compur, but the principle of their
action is somewhat different, The following description is given to
show how the same aim may be- achieved by a different mechanical
design.

In the Cumpur shutter the bird pawl performed the action of
opening and closing the blades. In the present case the action can
best be compared with a toggle switch, slipping when pulled one way
and engaging when released.

Fig. 4.36 shows the setting lever which is connected to the hooking
arm. As in the Compur shutter, a small movement of the blades
actuating ring is sufficient, to open the shutter. If left alone, the
blades actuating ring will close the blades under the action of its

own spring, The blades actuating ring is situated on one side of the
shutter easing and can bo moved from the other side by its pin

126

MINATURE CAMERA CONSTRUCTION

which projects through a small hole In the casing. The selling

lever itself is spring-loaded, in the direction shown in Fig. 4.37 so
that force is needed to tension it. When the shutter is tensioned, i.e.,
toe selling ring end is pulled by the photographer; the lever .starts to
route

and the

hooking

arm

moves

as

shown.

It

slips

underneath

the
blades actuating ring pin because the cut-out in the hooking arm Is
slightly

chamfered

(Fig, 4.37),

As the tensioning movement continues, the attachment point of

the hooking lever travels on the periphery so that the cut-out portion
of the hooking lever slips back to embrace the blades actuating ring
pin. This time, however, the pin is located deeper in the cut-out and
there is no possibility of the inclined portion allowing it to slip.
When the tensioning movement is completed, the release catch C

(Fig. 4.38) engages the protruberance on the setting lever. The catch
C is connected via. the link lever C ; the release lever. When this is

pressed,

it

pulls

the

link

lever

and

rotates

the

catch lever

G ;

this

in
turn releases the setting lever which is now free to rotate under the
action of its powerful spring. The hooking arm pushes the pin on
the actuating arm of the blades and then as the setting lever con­tinues to revolve, the hooking arm pulls the pin backward and thus

closes the blades.

The setting lever has another flat on it which on rotating engages

127

MINIATURE AND PRECISION CAMERAS

MINIATURE CAMERA CONSTRUCTlON

the braking lever (Fig. 4.39), The retarding lever a part of the
pallet arrangement. When the setting lever spring alone decides on
the shutter speed, additional spring is brought into play to increase

its tension (Fig. 4.40).

There are, therefore, several possible timing arrangements. On

1/300 sec no delating device is introduced. At 1/100 sec the spring

makes the setting lever revolve and the braking lever is engaged for
a moment, making the gears in the gear train revolve, but the pallet
wheel is out of action. At 1/50 sec and 1/25 sec the engagement of

the quadrant increases and at 1/10 sec the pallet is engaged in the

pallet, wheel, Then, with the pallet engaged, the times of 1/5, 1/2 and

1 sec are achieved, by gradually increasing the insertion of the
quadrant wheel and thus the braking arm delays the setting lever for
a correspondingly longer time. All the actions listed above are

controlled by the speed control ring (Fig. 4.41).

On the bulb setting the B arm is allowed to impede the setting

lever arm, Arm B is tensioned anti-clockwise by the spring. As the
release lever is pressed, the pin on the catching arm is lowered and
arm B can arrest the setting fever on its way back after it has already

opened the blades. On releasing the pressure on the- release lever,
arm B is withdrawn and the setting lever can complete its travel,

To allow for the fixed delay time before the shutter can be operated

(for self portraiture), the actuating ring of the blades has, besides the

pin by which it is operated, an additional arm which may be pre-

vented from moving by the delay mechanism. The prevention is
performed by a quadrant gear with a cut-out sector into which the
inn on the

blades actuating ring

can

enter,

once

the

quadrant gear
has suitably revolved, The time of revolution of the quadrant gear
constitutes the delay time. The setting of the delay tensioning is
effected by a lever directly connected to the quadrant wheel and held

by an auxiliary release lever (Fig. 4.42), Upon pressing the shutter
release, the shutter setting arm is freed and moves through a small
angle, sufficient to operate the release which trips the delay
mechanism. This latter mechanism arrests the movement by the
actuating ring of the blades when it has completed, its travel.

The problem of synchronization will be more fully dealt with inter
in Chapter 6. The present trend in camera construction is to dispense
with external synchronizers and make the shutter of the camera
pro vide the necessary synchronizing mechanism. It required much
ingenuity to crowd one more mechanism into the alreadv over-

crowded space in the interlens shutter, but this has been now

successfully accomplished. by all the leading manufacturers. There

are two possible delay schemes. One is designed for expendable

flash

bulbs

and the

shutter

is

arranged

to

open

some

short

time

after

179

MINIATURE AND PREC1SION CAMERAS

the electrical contact have closed and started the ignition of the
primer in the bulbs. The delay in this case is of the order of 20
millisec. The other arrangement provides for the use of the electronic
flash

where

the

shutter

must

be

fully

open

during

the

very short time
of both the triggering and firing of the electronic flash. In this case
there is no delay whatsoever and the contacts are closed at the
full opening of the shutter

These two synchronizing problems have been successfully solved

by the designer of the Prontor SV shutter, The commonly accepted

Fig, 4.43—Prontor
ment

of the

anti-clockwise and make the contact, (b) In the X position the
X-M lever prevents the rotation of the M-Contact spring. (c) The
projection on the X-M ring engages the arm of the pallet gear train

blades actuating

SV

fully

synchronized shutter,
ring

allows

and disengages it at thc M position,

the

M-contact

(a) The

spring

move-

to tip

continental marking denotes X as the instantaneous flash (no delay)

setting and M as the 20 millisec delay setting,

M setting, When the release lever is pressed, its first section is to

free the setting lever. The initial small rotation of the setting lever

moves the setting ring of the blades through a small angle
insufficient to open the blades but large enough to trip the delay
mechanism, in the same period the fash contacts are closed Fig,

4.43). To achieve a much smaller delay than that normally afforded

130

MlNATURE CAMERA CONSTRUCTION

by the delay mechanism, its pallet wheel is disengaged by the lever
operated by the synchronizing arm in. the M position (Fig. 4.43c).

Thus the delay mechanism works only due to the inertia of the gear

train

this

being designed

to

provide, together

with

the

shutter

inertia

a delay of approximately 20 millisec, On completing its action, the
delay mechanism rotates the quadrant wheel sufficiently to free the
actuating ring of the blades and these are then opened and closed
in the normal manner. The speed of opening and closing is controlled

by the escapement mechanism (not to be confused with the delay

mechanism) and governed by the position of the cam ring.

X setting. Fig. 4.43 shows the double set of electrical contacts

inside the shutter with the synchronizing arm set to the M position.
We saw that the small movement of the actuating ring allowed the M
contact to rotate anti-clockwise and touch the cent re conductor of Hie
flash contact (Fig. 4.43a). When, however, the synchronizing
arm is set to the X position (Fig. 4.43b) the synchronizing arm
prevents the. tipping of the M contact. The synchronizing is per-

formed by the X contact which is linked to the hooking arm (Fig.

4.43b) and so arranged as to touch the flash contact when the blades
are fully open.

131