Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual download pdf (Page 10)

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Using The Viewfinder

As with most astronomical telescopes,

the ETX model telescopes present a

fairly narrow field of view to the observer.

As a result it is sometimes difficult to

locate and center objects in the

telescope’s field of view. The viewfinder,

by contrast, is a low-power, wide-field

sighting scope with crosshairs that let

you easily center objects in the eyepiece

of the main telescope’s field of view. The

telescope viewfinder is a great help in

locating faint astronomical objects before

you begin observing through the

telescope eyepiece.

ETX-90EC 8 x 21mm Erect-Image Viewfinder:

Standard equipment with the ETX-90EC, the 8 x 21mm Erect-Image Viewfinder has 8-power magnification

and an aperture of 21mm. This viewfinder presents a correctly oriented image both up-and-down and

left-to-right.

ETX-105EC or ETX-125EC 8 x 25mm Right-Angle Viewfinder:

Standard equipment with the ETX-105EC and ETX-125EC, the 8 x 25mm Right-Angle Viewfinder has 8-

power magnification and an aperture of 25mm. This viewfinder presents a correctly oriented image up-

and-down, but is reversed left-for-right.

Focusing the Viewfinder

The ETX model viewfinders are pre-focused at the factory. Individual eye variations may require that the

viewfinder be re-focused. To check the focus, point the viewfinder at a distant terrestrial (land) object such

as a telephone pole or light pole and look through the viewfinder. If the viewfinder image is not in sharp

focus, follow the procedure below that applies to your telescope model.

ETX-90EC

1. Remove the viewfinder by slightly unthreading the six alignment screws (4 and 6, Fig. 6) and slipping it

out of the bracket.

2. Loosen the knurled lock-ring (2, Fig. 6) located near the viewfinder’s front lens cell (1, Fig. 6). Unthread

this ring (counterclockwise, as seen from the eyepiece-end of the viewfinder) by several turns.

3. Look through the viewfinder and focus on a distant object. Slowly rotate the front lens cell in one direction

or the other, until the object appears sharp. One or two rotations of the lens may have a significant effect

on image focus.

4. Lock the focus in place by threading the knurled lock-ring clockwise up against the viewfinder’s lens cell.

5. Replace the viewfinder into the viewfinder bracket. Gently tighten the six alignment screws. Proceed with

Aligning the Viewfinder.

ETX-105EC or ETX-125EC

Turn the focus ring (2, Fig. 6) at the base

of the viewfinder eyepiece (3, Fig. 6) in

either direction until a sharp focus is

reached.

Aligning the Viewfinder

In order for the viewfinder to be useful, it

must first be aligned with the main

telescope, so that both the viewfinder and

the main telescope are pointing at

precisely the same location. To align the

viewfinder:

1. Turn the three rear alignment screws

of the viewfinder bracket (6, Fig. 6) so

that the viewfinder tube is roughly

centered within the viewfinder bracket.

Tip: Do not overtighten the align-

ment screws. When tightening one

screw it may be necessary to loosen

one or both of the two other

alignment screws.

Fig. 5: Viewfinder Installation.

ETX-90EC Viewfinder

ETX-105EC/-125EC Right-Angle Viewfinder

Fig. 6: The Viewfinder. (1) Front lens cell; (2) Knurled lock-

ring (ETX-90EC) or focus ring (ETX-105EC and ETX-

125EC); (3) Viewfinder eyepiece; (4) Front alignment screws

(one not visible in photo); (5) Viewfinder bracket; (6) Rear

alignment screws (one not visible).

ETX-90EC

ETX-125EC

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Meade ETX Astro Telescope/ETX Spotting Scope Instruction Manual Page 10

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