Precise Polar Alignment - Meade 2080 Instruction Manual

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fork arm. After performing the polar alignment procedure,
center the star Polaris in the telescope field. Loosen
slightly the knurled central hub of each Declination setting
circle. Now turn each circle until it reads 89.2°, the Decli-
nation of Polaris, and then tighten down the knurled knobs,
avoiding any motion of the circles.
Once the latitude angle of the wedge has been fixed and
locked-in, according to the above procedure, it is not
necessary to repeat this operation each time the telescope
is used, unless you move a considerable distance North or
South from your original observing position. (Approximately
70 miles movement in North-South observing position is
equivalent to 10 in latitude ch~nge.) The wedge may be
detached from the field tripod and, so long as the latitude
angle setting is not altered, it will retain the correct
latitude setting when replaced on the tripod.
It should be emphasized that precise alignment of the
telescope's polar axis to the celestial pole for casual
visual observations is not necessary. Don't allow a time-
consuming-effort at lining up with the pole to interfere
with your basic enjoyment of the telescope. For long-
exposure photography, however, the ground rules are quite
different, and precise polar alignment is not only advis-
able, but almost essential.
PRECISE POLAR ALIGNMENT
Unless you intend to engage in long-exposure astrophotog-
raphy, it is not necessary to follow the precise polar
alignment procedure described in this section.
Notwithstanding the precision and sophistication of the
drive system supplied with the Meade Models 2080 a!ld2120,
the fewer tracking corrections required during the course of
a long-exposure photograph, the better. (For our purposes,
"long-exposure" means any photograph of about 10 minutes'
duration or longer.) In particular, the number of Declina-
tion corrections required is a direct function of the pre-
cision"of polar alignment.
The procedure described here should be implemented only
after the alignment procedures of the preceding section
have first been carried out.
Precise polar alignment requires the use of a crosshair
eyepiece. The Meade MA l2mm Illuminated Reticle Eyepiece
is well~suited in this application, but you will want to
increase the effective magnification through the use of