Shown is a 2-inch T-2 Mount attached to Canon EOS Rebel T3i.
Credit: Mike Barrett/www.wired4space.com
Star trailing was mentioned above and it can be used
to generate some lovely artistic effects, but generally
astrophotographers want pin-sharp stars and long
looked at the various types of telescopes and mounts.
through the night sky allowing longer exposures without
the stars trailing. However even with a telescope there
is always the bright moon that can be imaged.
Tracking
Camera Mounts
So far everything can be achieved with equipment
you may already have, but to track the celestial motion
you need to have an equatorial mount. This does not
mean that you have to buy an expensive telescope
mount though a tracking mount is a purchase you
may want to make when you get a little more serious
and want to start taking longer exposures. There are
a number of systems on the market: Astrotrac, Vixen
Polarie, and the iOptron SkyTracker are three popular
ones. They all work on the same basic principal: the
mount is aligned with the celestial pole (close to Polaris
20
20
in the northern hemisphere) then the camera mount is
rotated at the same rate as the stars revolve around
the pole.
All of these mounts are light, small and very
transportable, but require the addition of a tripod,
and some kind of tripod head. With the addition of a
simple programmable timer this makes for an excellent
portable astrophotography system. The exposure can
easily be increased from 30 seconds to 3 minutes even
with a 200mm telephoto lens. With this type of setup
you will be able to do some deep space photography
and if you are anything like me you will get the bug and
want to improve your skills and take your photography
to another level.
Conclusion
As can be seen astrophotography does not have
to involve huge expenditures and a lot can be done
with equipment that you may already own or have
access to. Obviously this is just an introduction to help
you get started, and there are so many more levels
to the subject. I will be covering some these in future
articles, including planetary imaging which can done
very easily using webcam.
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