|

Since there are different requirements for imaging than for visual observation,
the setup of your telescope will likely be slightly different for CCD imaging
than you may be used to for visual observing. Everything must be more
precise when it comes to imaging: alignment, balance, tracking, and focus all must
be more accurate than is necessary for viewing.
Location, Location, Location
Where you set up for CCD imaging is critical. Unstable platforms,
limited views, and light breezes that might otherwise go unnoticed during visual
observing become sources or frustration when imaging.
Decks and flat roofs often provide a means of escaping neighbors' lights or
getting above the trees and other obstructions. However, no matter how
well built, decks and roofs are notoriously bad imaging locations.
Vibrations are easily induced by the slightest movement of the observer.
These vibrations quickly ruin pictures, manifesting themselves as trailed or blurry images.
Consider where you will be aiming your telescope. Light sources which
are easily blocked by a hand while viewing can cause trouble for imaging. A
small tree branch which may not be noticeable through the eyepiece can blur a
picture. Also, keep in mind local sources of bad seeing, or atmospheric
turbulence. Roofs, chimneys, and roads all give off heat during the night
which can lead to mushy images if the telescope is pointed in their
direction. And remember that you will sometimes be imaging objects fainter
than you would normally view, so you may aim toward a section of the sky you
would avoid when visually observing.
Wind causes plenty of headaches for imagers. On a real windy night it
is probably best to stay indoors, or at least stick to visual observing.
However, you would hate to have an otherwise perfect night ruined by a little
breeze. If you can set up in a location which is protected somewhat from
the wind, it will make imaging much easier.
Obviously, finding the perfect location satisfying all of the above
requirements will be difficult, if not impossible, but getting the best spot you
can will be rewarded with better images. Some careful planning before dark
always pays off!
Computerized Telescopes
If you are using a goto or other type of computer-controlled telescope, you
may wish to perform an alignment before attaching the CCD camera. However,
keep in mind that you will have to rebalance your telescope with the new
equipment in place. Unless your telescope is using optical encoders (such
as with digital setting circles, or using a Celestron Ultima 2000 goto scope) you will
likely have to realign the scope's computer after rebalancing. Most goto
telescope lose their alignment if moved manually; manual movement is required to
achieve balance.
To align after attaching a CCD camera, you will have to use the CCD to
determine when an alignment star is properly centered in the telescope.
See the section on Finding objects for more
details on this procedure.
Setup Tips
Every telescope will be different in its setup for CCD imaging. Many of
the specifics for each type of scope are covered in the sections on
Balancing
and Polar Aligning. Below are some
helpful tips which apply to most every telescope used for imaging.
-
Lower the Tripod. Most telescopes have adjustable tripod legs for
leveling and height adjustment. When you observe visually you might
set the legs higher to accommodate a comfortable viewing position.
However, since for CCD imaging you will not be looking through an eyepiece,
you can lower the tripod to provide additional stability and wind
protection. Just remember if you are in your backyard to leave it high
enough that you can see your targets over any obstructions like fences or
houses, and to be able to see Polaris for polar aligning.
-
Know Where All Your Equipment Is. It may seem obvious now, but you might be
surprised what you can forget in the dark! Once the sun is gone and
the stars are out you will want to easily locate your equipment and avoid
tripping over any wires or the telescope tripod. Keeping everything
close at hand will help a lot once you start imaging. You won't want
to be hunting for a star chart and potentially bump your scope during an
image! A handy item is a large table (preferably one that folds for
easy storage and transportation) to set your laptop computer on, along with
accessories, charts, etc. It is a good idea to always lay everything
out in the same manner each time you setup. For example, I always place
my table in exactly the same location relative to my tripod (on the west
side), I put the battery in exactly the same spot next to the tripod (on the
northwest side), I lay out my computer and camera in the same way on the
observing table (laptop on the left or west side, power supply for the camera
on the very right edge, closest to the telescope), and so on. Power
cords always run in the same locations to avoid tripping and tangling, etc.
Next, Balancing a Telescope....

Next Page
|