as the Moon, filtered Sun and bright planets. Afocal imaging can also be
performed successfully with certain camera phones.Camera Summary
Camera Type Typical Targets
Mobile phone camera Low-resolution and
wide-field Moon, bright
planets and filtered Sun
Point-and-shoot camera Landscape shots,
constellations, general stars
High-end point-and-shoot Landscape shots, deep sky,
(prosumer) camera full-disc Moon
DSLR Deep sky, landscapes, full-
disc Moon, full-disc filtered
Sun, general stars and
constellations
Webcams High-resolution Moon, bright
planets and filtered Sun
Dedicated high frame rate High-resolution Moon, bright
planetary camera planets and filtered Sun
Cooled CCD camera Deep sky
Astronomical video camera Wide-angle night sky (e.g.
meteor showers, satellites), Moon, filtered Sun, bright
planets, deep skyAfocal imaging can be done by hand holding the camera in place but it’s not
easy to make sure the camera is focused, set correctly and pointing squarely
down the eyepiece. In addition, pressing the shutter button can create
unwanted movement, blurring the end result. For the best afocal images, it
is necessary to hold the front surface of the camera lens as close as possible
to the outward lens surface of the eyepiece but it’s also important to avoid
direct contact as glass on glass will almost certainly cause scratches.
One solution to this is to use an afocal coupling platform, available from
many astronomical stockists. This locks on to your telescope’s eyepiece
holder and keeps the camera securely in place, providing the means
necessary to adjust the camera’s position for optimal results. A remote
shutter-release cable can then be used to activate a camera’s shutter
without direct contact. As an alternative, a camera’s shutter-delay timer can
also be used to the same effect, giving a few seconds for any touch-induced
wobbles to disappear before the shutter opens.Astronomical Video Cameras
Low-light video cameras are now available for astrovideography, the
process of taking video footage of astronomical objects. These can be fitted
into the eyepiece barrel of a telescope producing a "live" image of what the
telescope can see. These are especially good for group activities where a
procession of observers waiting to look through the eyepiece of a telescope
needs to be avoided.
A widefield video lens fitted to these cameras produces a view of large
areas of the night sky which are far deeper than you can see with just your
eyes. This makes video astronomy particularly good for meteor showers,
where the whole shower can effectively be recorded and played back at your
own leisure.Cameras and Lenses
In order for a digital camera to perform its primary function, focused light
must be delivered to its sensor. This is achieved by fitting a lens to the front
of the camera. Some cameras, such as those found in camera phones and
point-and-shoot models, have fixed lenses fitted. Others, such as DSLRs
and astronomical CCD cameras, are camera bodies on to which a variety of
different lenses can be fitted.
Whether or not the lens can be removed from your camera determines
the type of imaging you can do. Fixed-lens cameras have less natural
flexibility, being constrained to take wide-angle sky shots the size of which
is determined by the focal length of the attached lens. They can also be used
in conjunction with a telescope for afocal imaging, the basic technique of
pointing the camera down the eyepiece. This works for bright objects such[8] A DSLR camera adapter ring.
[9] A point-and-shoot camera mounted on an afocal coupling platform.89Astronomer Book