A description of the German AA pivoted ring sight Schwebekreisvisier 30/38 appeared
in Tactical and Technical Trends No. 41 p. 4, but a sketch of the
instrument was not available for that issue. The accompanying sketches and
brief resume of the method of operation supplement the article referred to above.
The speed of the target must be quickly estimated, and the appropriate
pivoted ring, and corresponding scale, inserted. The layer presses his eye to the
eyepiece and by operating the traversing gear, displaces the bead of the foresight
in the apparent line of flight of the target to a point so far in front of the target
that its nose cuts the rim of the pivoted ring, and the target is heading from that
position to the foresight bead. The ring is pivoted, according to the angle of sight, to
the target so that at angles near 0° it will be almost horizontal and will appear
to the layer to be a line, of which the bead will be a thickening.
If, in the case of a surprise attack, there is no time to align the target
exactly along the ring, the layer must at least keep the foresight bead ahead and
in the line of flight of the target.
The sight is only intended to be used to direct the opening rounds; after that, fire
is continued in accordance with observation of tracer. The sight is not
used for the engagement of ground targets.