Bushnell 78-6000 Telescope USE Selecting AN Eyepiece, Focusing Telescope, Aligning Finderscope

TELESCOPE USE

SELECTING AN EYEPIECE:

1.You should always start viewing with the lowest power eyepiece, which in this case is the 25 mm lens. Note: the base power of each eyepiece is determined by the focal length of the telescope objective element, which for this model is 1000 mm. A formula can be used to determine the power of each eyepiece: telescope OBJECTIVE mirror focal length

EYEPIECE focal length = MAGNIFICATION (e.g. Using the 25 mm lens, the calculation would look like this: 1200 mm ÷ 25mm = 48x or 48 power.)

2.Offered as an accessory for this telescope is a Barlow lens (model #78-0105). Barlow lenses are used to double or triple the power of your telescope by placing your Barlow between the focusing tube and the eyepiece. Using the example above, a 2x Barlow lens would give you a total power of 96x or 96 power. (48 x 2 = 96x or 96 power). Other accessories available include a 9mm eyepiece (model #78-0101) that would give you 133x or 133 power or 266x when used in conjunction with the Barlow accessory and a standard camera adapter (model #78-0104) for photographing the night sky.

FOCUSING TELESCOPE:

1.After inserting the eyepiece, aim the main telescope tube at a land-based target at least 200 yards away (e.g. A telephone pole or building). Fully extend focusing tube by turning Rack & Pinion Focusing Mechanism (1)

2.While looking through selected eyepiece (in this case the 25 mm), slowly retract focusing tube by turning Rack & Pinion Focusing Mechanism (1) until object comes into focus.

ALIGNING FINDERSCOPE:

1.Look through low-power 1.25" format eyepiece (9) and establish a well-defined target (see focusing telescope section).

2.Looking through Finderscope (8), alternate tightening each Finderscope Adjustment Screw surrounding the Finderscope (8) in the Finderscope Mount until crosshairs of Finderscope (8) are precisely centered on the same object already centered in Main Telescope Tube's field of view as seen through the 1.25" Format Eyepiece (9).

3.Now, objects located first with the Finderscope (8) will be centered in the field of view of the main telescope as seen through the 1.25" Format Eyepiece (9).

COLLIMATING THE TELESCOPE

Good alignment or collimation of the telescope's optical components will guarantee the most optimum viewing. This telescope body comes preassembled from the factory and precollimated. Therefore collimation should not be required. However, due to its great importance there are a few steps that you can take to ensure that your telescope is properly collimated.

1.Remove the 1.25" Format Eyepiece (9) from the Rack and Pinion Focusing Mechanism (1).

2.Look into the Rack and Pinion Focusing Mechanism (1) with the eyepiece removed. You will see the secondary mirror located a few inches inside the end of the telescope tube (nearest the Rack and Pinion Focusing Mechanism). Since it is a mirror, you will see a reflection of the large primary mirror (7). That mirror will show an image of the secondary mirror and your eye. Each image will be centered in a concentric set of images starting with the image of the Primary Mirror (7), the secondary mirror, and your eye.

3.Please refer to the diagram to see what to expect.