TM 5-6675-250-20
1 - 1 1 . T E C H N I C A L P R I N C I P L E S O F O P E R A T I O N ( C o n t i n u e d )
(11)
(12)
(13)
(14)
Telescope focus control (11).
Permits the operator to adjust the focal length of the tele-
scope to see a target.
Reticle illumination control (12).
Adjusts the intensity of the lighting of the reticle pattern
d u r i n g n i g h t o p e r a t i o n s.
M i c r o s c o p e f o c u s ( 1 3 ) . Permits the operator to adjust the focus of the microscope to
present a clear, sharp image of the optical scales.
Magnetic compass plunger (14).
Locks the compass needle in a fixed position to protect it
from vibration and shock when not in use. Pressing the plunger releases the locking mecha-
nism and permits the spring-mounted needle to move freely.
Plate level (15).
Indicates the level of the theodolite and the GRU.
Horizontal circle setting control (16). U s e d t o s e t t h e h o r i z o n t a l c i r c l e d u r i n g t h e o d o l i te
c a l i b r a t i o n .
Mounting plate and reference mirror (17).
Used for aligning the theodolite horizontal circle
with the follow-up by providing a fixed reference point.
R e t i c l e f o c u s c o n t r o l ( 1 8 ).
Permits the operator to adjust the reticle pattern to a sharp
f o c u s . T h e r e t i c l e f o c u s c o n t r o l i s u s e d i n c o n j u n c t i o n w i t h t h e r e t i c l e l a m p i l l u m i n a t i on
control during night use.
1-13
