TM 9-1556
4-6
ORDNANCE MAINTENANCE-OBSERVATION TELESCOPES M48 AND M49
b. The major units of Observation Telescope M48 are the ob-
jective assembly, body tube, prism housing assembly, and focusing
mechanism with eyepiece assembly.
c. The front of the telescope has a sliding sunshade which can
be extended approximately 2 inches as the need requires.
d. The telescope is furnished with an objective cover and eye-
piece cap. These are screwed into place to protect the lenses when
the telescope is not in use.
e. The telescope is focused by pushing or pulling the eyepiece in
or out until an approximate focus is reached, and then turning the
knurled focusing sleeve to obtain exact focus. This arrangement is
made possible by a spring-loaded ball which either rides over the
threads of the focusing nut, when the eyepiece is pushed or pulled,
or engages the threads when the eyepiece is turned.
5. OBSERVATION TELESCOPE M49.
a. Observation Telescope M49 (fig. 2) is a 20-power telescope
having a field of view of 2 degrees 12 minutes and an exit pupil
diameter of 0.108 inch. The image is erected by a porro prism system.
The over-all length of the telescope is approximately 14 inches.
b. The major units of Observation Telescope M49 are the ob-
jective assembly, the body tube, the prism housing assembly, and
the focusing mechanism with eyepiece assembly.
c. Observation Telescope M49 does not have an adjustable sun-
shade. Instead, the front end of the body tube extends approximately
three-quarters of an inch beyond the objective, thereby providing a
permanent sunshade.
d. The telescope is furnished with an objective cover and an
eyepiece cap. These are screwed into place to protect the lenses when
the telescope is not in use.
e. The telescope is focused by turning the knurled focusing
sleeve.
6. ACCESSORIES.
a. Accessories for Observation Telescopes M48 and M49 include
a carrying case for each telescope, a tripod for each telescope, and a
carrying case for each tripod. These accessories are described in the
paragraphs immediately following in this section.