Bushnell Model 78-9570 - Manual (Page 3)

HOW TO USE YOUR NEW TELESCOPE
Astronomical telescopes are designed in such a way that the image you see appears
UPSIDE DOWN and REVERSED, this is acceptable for viewing celestial bodies.
Selecting an Eyepiece:
1. Always begin viewing with the lowest power eyepiece, which in this case is the 20mm lens. Note: the base
power of each eyepiece is determined by the focal length of the telescope objective lens, which for this model
is 910 mm. A formula can be used to determine the power of each eyepiece:
telescope OBJECTIVE lens
focal length EYEPIECE focal length = MAGNIFICATION (e.g. Using the 20 mm lens, the calculation
would look like this: 910mm
÷ 20mm = 46x or 46 power.)
2. To select the 20mm eyepiece, position the Rotary Power Turret® (14) so that the 20mm eyepiece is in line
with the Ocular Alignment Arrow.
3. Included in the
Accessory Turret (15) is a Barlow lens. Barlow lenses are used to double or triple the power
of your telescope. Using the example above, your 2.5x Barlow lens would give you a total power of 115x or
115 power. (46 x 2.5 = 115x or 115 power).
4. The full moon can be so bright that distinct surface details are difficult to view and prolonged viewing is
uncomfortable. Included in the Accessory Turret® (15) is a Moon Filter. Moon Filters are specially tinted
lenses that reduce the glare of the moon so that enjoyable viewing can take place.
Focusing Telescope:
1. After selecting the desired eyepiece, aim main telescope tube at a land-based target at least 200 yards away
(e.g. telephone pole or building). Fully extend focusing tube by turning Rack and Pinion Focusing
Mechanism (12).
2. While looking through selected eyepiece (in this case the 20 mm), slowly retract focusing tube by turning
Rack and Pinion Focusing Mechanism until object comes into focus.
Aligning Finderscope:
Remove plastic insert on bottom side of finderscope to allow battery to make connection with battery contact for
power. Turn power switch on. See finderscope page.
Look through main telescope tube at low power and establish a well-defined stationary target. Looking through
red dot finderscope, alternate tightening each adjustment wheel (at rear and left side of finderscope) until the red
dot of finderscope is precisely aligned and centered on the same object being viewed in main telescope tube.
See finderscope page.
Now, objects located first with the Finderscope (16) will be centered in the main telescope.
Viewing Land-Based Objects:
1. The T-18 Erecting Lens will correct the normally upside down and reversed image so that you can easily
enjoy observing land-based objects through your compact telescope.
2. Simply insert the T-18 Erecting Lens into the T-18 Erecting Lens Receptor (13).
3. Repeat focusing directions as described above except that you will be looking through the T-18 Erecting Lens
instead of the 20mm eyepiece. Note: When the T-18 Erecting Lens is inserted into the T-18 Erecting Lens
Receptor (13) the Eyepieces contained in the Rotary Power Turret® (14) will be inoperable. Remove the
T-18 Erecting Lens to regain eyepiece functionality.
Transporting and Storing Telescope:
1. Loosen tripod-locking screws and collapse each tripod leg section. Collapse Tripod Leg Brace (8) and pull
all three tripod legs together. Loosen Vertical Adjustment Lock (4) and tilt objective end of telescope
toward tripod legs. Slip telescope into carrying case and pull drawstring to close.