Using The Viewfinder; Focusing The Viewfinder; Aligning The Viewfinder - Meade ETX-105EC Instruction Manual

Meade instruments astro telescope instruction manual
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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
telescope eyepiece.
ETX-90EC 8 x 21 mm 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 25 mm 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.
ETX-90EC Viewfinder
2
ETX-105EC/-125EC Right-Angle Viewfinder
the
Fig. 5: Viewfinder Installation.
3
2
ETX-125EC
1
2
ETX-90EC
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).
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1
4
5
3
6

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Etx-125ecEtx-90ec

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