5 
C. Zeiss vertical sighting periscope (left and right view) 
Flughohe 
übzr Grund 
Fig. 3 "Lotfe' 
“visual compensation“ would be far too inac 
curate for navigational purposes. A particu 
larly practical, gyro-supported drift indica 
tor is the C. Zeiss vertical sighting periscope 
( Lotfe). 
On this Lotfe, the cross-hairs of the obser 
vation telescope which are designed as a lu 
minous mark, are stabilized by a gyroscope. 
It need hardly be emphasized that when the 
equipment is installed in the airplane it must be 
aligned with the greatest accuracy ( + V4 0 ) 
in azimuth with reference to the longitudinal 
axis of the ship. 
The gyroscope of the Lotfe is pendulum- 
mounted so that its axis is exactly perpendi- 
This is not possible with direct observation 
from high flight altitudes. 
Furthermore, an auxiliary prism permits 
to displace the gyro-supported crosshairs of 
the Lotfe in the forward direction thus allow 
ing to pick up a distant target which is on the 
course of the airplane. If allowance for the fly 
ing height above the ground has been made in 
the instrument, and the crosshairs and the wan 
dering picture of the terrain have been vi 
sually synchronized, the sighting prism is ad 
justed by a tangential-speed motor in such 
manner that once the distant target has been 
picked up, it remains exactly in the point of 
intersection of the crosshairs during the ap- 
which are not gyro-supported give an inter 
mittent picture of the terrain with reference 
to the drift indicator mark. The drift which 
is thus more or less precisely ascertained by 
cular. This permits to sight vertically down 
ward so that the lateral displacement can be 
determined with a high degree of precision 
when flying over a predetermined guide point. 
Geschwindigkeit über Grund 
nchronisierung 
Kreiselschalter