so that the average moment corresponding to
the maximum opening of the diaphragm during
the exposure of each camera may be perfectly
synchronous.
Such an optimization of the synchroni-
zation represents a very hard work and of a
special fineness.
We shall develop further on the way we
have carried out the operation of determining
the effective time considering the diaphragm
opened at each cameras as well as the synchro-
nization of both cameras and the optimization
of this synchronization.
The assembling used consists of register-
ing the exposure times of the two cameras,
which were specially changed into projection
cameras, the registering being made on a ro-
tary cylinder covered with photosensitive
material. Fig.3
Since during the exposure the cylinder
rotates with a known constant speed the light
spots, projected on the photosensitive mate-
rial wound around the rotary cylinder shall
be registered as parallel strips.
The length of each strip will be propor-
tional to the exposure time corresponding to
the camera which has projected the spot.
The photo-sensitive material was printed
beforehand with lines parallel to the genera-
trix of the rotary cylinder and the photo-
grammetric cameras were placed so as to pro-
ject the light spot on the same generatrix
of the cylinder.
From the difference of the lenghs of the
strips generated by the spots projected on
the rotary cylinder by the caneras we can meas
sure the times t' and t" representing the pe-
riod when each diaphragm has been opened
The relationship permitting the mea-
suring of the exposure times t' and t" is
1
& QT 1
1. P z here:
ea SEN. EN
r = radius of the rotary cylinder
N = number of revolutions per second
1' and respective 1" = the lengths of the
,8trips generated by
the light spot. Fig. 4
From the difference recorded among the
strips in relation to the lines printed be-
forehand on the photo-sensitive material pa-
rallel to the generatrix of the rotary cylin-
der it may be determined the non-synchroniza-
tion of the cameras concerning the opening
and closing of diaphragms.
Noting with tg the passing moment of
one of the lines printed beforehand on the
photo-sensitive material ( which became a
datum line), and with t, and t4 the moments
when the exposures of the two cameras have
begun and finished, respectively, we have
the relationship:
At =(t,- t) -( t4- t) representing the
2
exposure non-synchronization and where we
have:
tib, o l1 tt =
9 2 Ye ” A
=
2]lpN rN
d
2 where:
li and 1, are the abscisas of the ends
of each length in relation to the datum line.
The exposure optimizing is ensured by
bringing the middes of the lengths registered
at the rotary cylinder on the same line and
acting the synchronization device, so that
the moments Sm and to corresponding to the
m
OBSCURA CAMERA
REVOLUTION
RECORDER
CYLINDER WITH
PHOTOGRAPHIC FILM
CAMERA CONTROL
DEVICE (U.M.wJT
ENGINE WITH POTEN-
TIOMETER FOR REVOS
LUTION ADJUSTMENT
$4,929. LIGHTING FITTING
220 v-49v
CAMERA CONTROL
ige 3 Schematic circuit for checking
and adjusting the synchronization
60