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