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The following magnification values are achieved when using the Barlow lens and the
interchangeable eyepieces:
Eyepiece Power Power With 2X Barlow Lens
25 mm
30X 60X
4 mm
187.5X 375X
The level of magnification required depends on the object being observed. Optimal
performance is obtained if the magnification is typically not more than about 30X for
every 10 mm of objective lens diameter. Magnification of around 450X or less is ideal
for a telescope with a 152-mm diameter objective lens and is best for observing most
celestial objects. A lower magnification power and a wider field of view are advisable for
observing galaxies and nebulae. The highest magnification power should be used for
detailed observations of the moon, Jupiter, Saturn or any object that is quite bright.
The highest magnification power of the Barlow lens/4-mm eyepiece combination should
only be used for large or bright objects such as the moon and the brightest planets.
ABOUT YOUR NEWTONIAN REFLECTOR TELESCOPE
Your telescope is a Newtonian reflector. Light enters the open end of the tube and
travels down to the opposite end where it strikes a specially curved mirror, known as the
primary mirror. The focused image is reflected back up the tube to a small, flat mirror
near the open tube end, called the secondary
mirror. This secondary mirror reflects the
focused image out through the side of the
telescope tube to the eyepiece holder where it is
enlarged for viewing through the eyepiece.
The primary mirror is a precision ground and
polished component that is precisely positioned
at one end of the optical tube. It is pre-aligned
for maximum peformance at the factory and
should not need any adjustment.
Therefore,
never adjust or remove any of the screws
located at this end of the optical tube. Doing
so will void your warranty and degrade the
(Fig. 28)
performance of your telescope.
(See Fig. 28)
USING YOUR TELESCOPE
1) Take your telescope outside. Viewing objects through closed or open windows is not
recommended. Your view can be distorted by reflections in the glass of a closed
window or by air currents of differing temperatures passing through an open window.
2) Let your telescope adjust to the outside temperature. Your telescope will perform
much better if the temperature of the mirrors, eyepiece lenses, and the air inside the
