Orion 52083 - Manual (Page 31)

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Using The SSDSMI-2 As An Autoguider
A great feature of the SSDSMI-2 is its ability to be used as an autoguider for
telescope mounts. You can use the SSDSMI-2 to autoguide a mount while
images are being taken with another camera, such as a DSLR or another
SSDSMI-2.
Tracking errors are usually sufficiently small on short duration images (15 to
90 seconds depending on the mount) that guiding is not required. Therefore
a series of short exposure images can be taken and combined together later
using the Combine command. However, in many cases a single long exposure
is superior due to the elimination of extra readout noise and the residual blur-
ring caused in realigning the images.
When taking long exposures with astronomical telescopes, motorized tracking
is required to compensate for the Earth’s rotation. Most telescope mounts do
not track accurately enough for long-exposure imaging without some form of
additional “guiding”. Manual guiding can be done by an observer watching a
star (“guide star”) through a telescope (“guide scope”) mounted next to the
main imaging telescope (on the same mount). The observer makes manual
corrections to the motor drives via a pushbutton hand controller to keep the
star centered in the guide scope’s eyepiece over time. In this way the track-
ing accuracy of the main telescope (with imaging camera attached) can be
assured. Stars in the resultant images will be crisp and round. Manual guiding
can be very tiresome and tedious, however, especially if taking many long
exposures throughout the night.
The SSDSMI-2 can be used as an “autoguider” to take the place of the
observer so that no manual guiding corrections are needed during long expo-
sure imaging. Keep in mind, however, that when the SSDSMI-2 is used in this
way, you will need another telescope and camera (such as a DSLR or a second
SSDSMI-2) on the mount to actually take images with; the SSDSMI-2 takes the
place of the observer viewing through the guide scope, but cannot autoguide
and image at the same time.
So, in order to use the SSDSMI-2 as an autoguider, the following equipment
will be required:
• Astronomical telescope mount capable of accepting autoguider drive com-
mands.
• Cable to connect computer (serial port) to mount’s autoguider jack (mount
specific).
• Main telescope for imaging.
• Camera for imaging.
• Guide scope for guiding.
• Any required rings or brackets for guide scope attachment to the mount
along with the main telescope.