Bushnell 78-9512 Telescope User Manual


 
HOW TO USE YOUR NEW TELESCOPE
Astronomical telescopes are designed such that the image you see will appear UPSIDE DOWN and REVERSED, this
is acceptable for viewing celestial bodies. For land-based viewing an “Erecting Lens” is used to properly re-orient the
image.
Selecting an eyepiece:
1. You should always start viewing with the lowest power eyepiece, which in this case is the 20 mm lens.
Note: the base power of each eyepiece is determined by the focal length of the telescope objective lens,
which for this model is 700 mm. A formula can be used to determine the power of each eyepiece lenses:
telescope OBJECTIVE lens focal length EYEPIECE focal length = MAGNIFICATION (e.g. Using the
20 mm lens, the calculation would look like this: 700 mm ÷ 20mm = 35x or 35 power.)
2. Included with this telescope is a Barlow lens. Barlow lenses are used to double or triple the power of your
telescope. Place your Barlow between the focusing tube and the eyepiece. Using the example above,
your 3x Barlow lens would give you a total power of 105x or 105 power. (35 x 3 = 105x or 105 power)
3. Also included with this telescope is an Erecting lens. An Erecting lens is used to view land-based object
where the correct image orientation is important. The Erecting lens re-orients the telescope image so
that the image you see is properly oriented. Place your Erecting lens between the focusing tube and the
eyepiece (fig. 3). It is not recommended to use the Diagonal Mirror (11) with the Erecting lens. The Diagonal
Mirror will make the erected image appear to be “flipped” depending on the orientation of the diagonal
mirror- relative to the telescope.
Focusing Telescope:
1. After selecting the desired eyepiece, aim Main Telescope
Tube (2) at a land-based target at least 200 yards away (e.g. A telephone pole or building). Fully extend
focusing tube by turning Rack and Pinion Focusing Mechanism. (10)
2. While looking through selected eyepiece (in this case the 20 mm), slowly retract focusing tube by turning
Rack and Pinion Focusing Mechanism (10) until object comes into focus.
Aligning Finderscope:
1. Look through Main Telescope Tube (2) and establish a well-defined target. (see focusing telescope section)
Tighten the Altitude Lock Knob (17) and Azimuth Lock Screw (4) so that telescope’s aim is not disturbed.
Looking through Finderscope (16), alternate tightening each Finderscope Adjustment Screw (15) until crosshairs
of Finderscope are precisely centered on the same object already centered in main telescope tube's field
of view.
2. Now, objects located first with the Finderscope (16) will be centered in the field of view of the main
telescope.
Never Look Directly At The Sun With Your Telescope
Permanent Damage To Your Eyes May Result.
fig. 3
12
10
Erecting Lens or Barlow Lens