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HEQ51EQ6
SynScan'".
SynScanTM
SynScanrM,
Dec
Dec
identifi and Dec
cyepiece
movcrnents,
(Fig.A-1).
Dec
Generally speaking the SynScan
T
M
produces pointing and tracking accuracies adaquate for most applications.
However, if higher precision is required, for example for astro
-
photography, accurate polar alignment and
"cone" error calibration may be required. See the manual for mount for information on accurate
polar alignment using the polarscope.
"Cone" error is a common inaccuracy found on all German equatorial mount. It is a result from the optical
axis not being aligned to the R.A. axis of the mount. This affects the pointing accuracy of the
Three
-
Star Alignment automatically compensates for the "Cone
"
error. If you choose One
-
Star or Two
-
Star
Alignment method, you will need to perform manual mount calibration to eliminate the "cone" error. The
following calibration procedure should be performed before the initial use of the telescope and periodically
thereafter to ensure the accuracy.
Testing for Cone Error
This test is done at night using two bright stars located on the opposite side of the sky. Make sure the
telescope is properly polar
-
aligned using the polarscope. Perform the One
-
star Alignment using an eastern
star as the alignment star (see One
-
star Alignment). After the star alignment, choose a bright star on the
western sky from the
object database and have the telescope slew to the star. If the optical axis
is perfectly aligned to the R.A. axis, the telescope will accurately put the star in the center of the eyepiece.
In this case, there is no "cone" error in your telescope setup and you will not need to perform the
calibration. It is acceptable if the star is slightly off
-
center as long as it is in the eyepeiece view and close to
the center. Many factors determine the pointing accuracy of the
for example incorrect star
alignment, R.A. or
lock knob being lose, or "cone" error. If your telescope puts the star outside the
eyepiece view, you need to first determine whether it is "cone" error that causes the pointing inaccuracy. To
find out, simply move the telescope in R.A. axis by pressing the Left or Right direction key. If the star can
be moved into the eyepiece view without adjusting the
axis, it is likely that "cone" error exists in your
telescope setup.
Calibration Procedure
1.
Insert the illuminated reticle eyepiece. Make sure that the telescope is properly set up and balanced, and
the finderscope is perfectly aligned with the telescope tube.
movements
Required accessory. Illuminated
in the reticle eyepiece. If you are already familiar reticle
Step
2
to
4
is to R.A.
with double
with the
you
may skip to step
5.
crossline pattern. Depending
on
the
design of your mounting plate
2.
Find any bright star and place it in the center of the
(dovetail bar), modifications may
eyepiece view.
be required. (See step
10
for the
3.
Look into the eyepiece. Move the telescope in R.A.
required mechanism on the
axis using the R.A. direction keys on the hand control
mounting plate.)
while carefully observing the movement of the star.
4.
Keep moving the the telescope in R.A. axis back and
forth to keep the star within the eyepiece view. Rotate
the eyepiece until the movement of the star becomes
parallel to (or matches) any set of the lines
This set of lines will represent R.A. movement in the
movement
course of this procedure, and the perpendicular lines
will represent
movement. Tigthen the set screws
to secure the eyepiece in place. Make sure that the
eyepiece will remain stationary when the telescope is
being rotated.
5. Point the telescope to North and set the latitude scale
to your local latitude using the altitude adjustment T
-
bolts, or place Polaris on the crosshair of the
polarscope if your polarscope is perfectly aligned with
the rotation axis of the mount.
eyepiece view