Polar Alignment; The Polar Alignment Viewfinder; Adjusting The Polar Viewfinder (Exos 2) - Bresser Goto-Kit Instruction Manual

Reticle LED
Fig. 4: The polar alignment
viewfinder
Fig. 5: The view inside the polar
alignment viewfinder reticle (the
four stars show an association
near the southern celestial pole)

Polar Alignment

The Polar Alignment Viewfinder

Normally, a rough alignment with the celestial pole is sufficient for visual pur-
poses. However, for those observers who need to meet the more demanding
knob
requirements of astrophotography, the polar alignment viewfinder allows the
b
telescope mount to be more precisely aligned with true North. The Exos2
Mount can be equipped with a red LED illumination for the finder scope (avail-
Eyepiece
able separately).
Adjusting the polar viewfinder (EXOS 2 only)
A. Calibrating the month circle at the polar viewfinder scope
(best done while daytime)
1. Point the viewfinder against a bright surface (not in any case at the sun!)
and see the scaled line with the center cross (Fig. 5). Turn the viewfinder's
eyepiece until the scales are focussed.
2. Now turn the month circle against the viewfinder until the 1st of May hits the
vertical line. The month circle is secured by a counterring; it should be able
to be turned but it should not come loose. Now you can put the viewfinder
back into the RA axis
3. On the month circle, there's a second scale, marked "E 20 10 0 10 20 W".
Take a white pencil and mark the point on the viewfinder that is right above
the "0". This can be also done by using a small piece of colored tape.
B. Aligning the viewfinder's optical axis to the RA axis (EXOS 2
only)
1. Starting at the polar home position, loosen the Dec lock, turn the Dec axis
by 90° and re-engage the Dec lock again. In this position, the optical axis of
the viewfinder is free.
2. Point the viewfinder at a terrestrial objekt like a phone pole, the tip of a
church tower or equiv. so that it lines up with the center cross of the reticle.
3. Ascertain whether the object moves out of the center cross when the mount
is rotated around its Dec axis.
4. If this is the case, correct 50% of the error by adjusting the hex screw of
the viewfinder holder. Now correct the remaining error by repositioning the
mount. Turn the RA axis by 90 / 180° and repeat this process until the cent-
er cross stays on the desired object.
Polar alignment by using the polar viewfinder
(EXOS 2 only)
1. Set the polar home position (see p. 8). Loosen the Dec lock, turn the Dec
axis by 90° and re-engage the lock.
2. Loosen the RA lock
3. Remove the dust caps
4. If not done yet, remove the isolaton pad from the viewfinder's illumination.
5. Turn the illuminator switch clockwise to a comfortable brightness and look
throug the viewfinder. If necessary, focus the viewfinder until reticle and
stars appear sharp.
6. In the following step 7, use the latitude adjustment screws and the azimuth
adjustment screws to do the necessary fine adjustments
Instruction Manual
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