The position of cameras having horizontal axes is such as to afford 
easy introduction of the focal value (ranging from 215 to 85 mm.). 
This is done by making the plate-holder and the two revolving 
arms (27-28) of the optical system slide on fairly horizontal guides 
(less than cp value). Said sliding is obtained with the aid of one single 
micrometric screw (df) (allowance 0,01 mm.). 
Since with the minimum focal it is possible to plot original photo 
graphs size 23 x 23 cm. so the instrument is also suited for plot 
ting super wide-angle shots (120°). 
d Drawing table. 
The drawing table as usually has sliding pencil-holders for X and Y 
and it is connected to the apparatus through mechanical transmis 
sion. It is located close to the operator so that one person only 
is required for handling. 
On request, we may establish electric connexion of the instrument 
with a large electronic table built by Officine Galileo. Anyway a 
back-lash gears is allowed, so that the scale between the optical 
model and the drawing may be varied to a remarkable extent. 
e Connection of the apparatus to a coordinates recorder. 
Possible use as a stereocomparator. 
The instrument provides three exit - shafts linked to the screws 
actioning carriages X, Y, Z; shafts afford connexion with a coordi 
nates recorder (especially to the recorder built by Officine Galileo). 
Owing to the high degree of accuracy that may be attained with 
this apparatus (especially if we consider also the use of correctors 
that will be hinted to later on), also its use as a stereocomparator 
might be a convenient one. 
Were this the case, after setting w = cp = o for both cameras, value 
Z might be kept as a fixed one (e. g. by setting Z = 3f), so that 
stereoscopic collimation at the various parts of the model requires 
variations in Bx and By. These values should be recorded at the 
same time as values X and Y taken up by the carriage of the coordi- 
f 
natograph. So if we consider a point i of the model, with ^ constant 
we shall have: