[7] Integrating video camera used for low-light astrovideo.
They can be thought of as a robust form of webcam, designed to capture
short-exposure still images at impressively high rates. The current crop of
cameras at the time of writing (2012) are able to record sequences of still
frames at up to 120 frames per second. Like a webcam, a planetary imaging
camera needs to be connected to a computer.Cooled Astronomical CCD Cameras
Long exposures using digital sensors do have a tendency to suffer from
noise – basically features in an image that shouldn’t be there. There
are many forms of noise and some are easier to deal with than others.
Random thermal noise is one of the harder ones to get rid of and is caused
by the generation of false signals due to thermal effects in the imaging
chip. One way to suppress thermal noise is to cool the imaging chip well
below the ambient temperature. There are various ways to do this, but the
most common is to use a cooling circuit which exploits the Peltier effect,
a thermoelectric cooling effect. Bringing the image sensor’s temperature
down by tens of degrees Celsius can reduce the effects of thermal noise to
a minimum. Cooled astronomical CCD cameras use this technique. Unlike
a stand-alone general-purpose camera, these cameras are designed to be
connected to and controlled by a computer.Camera Phones
Functional convergence now means that many models of mobile phone
have digital cameras built in and many of these are capable of taking basic
astronomical photographs of bright subjects.
Webcams (High-Frame-Rate Cameras)
There are certain models of webcam which can be used for high-frame-
rate imaging of bright Solar System objects. A bit of modification is
normally required to fit them to a telescope, and for many years, certain
models such as the Philips SPC-900NC produced images which were
impressive to say the least. Such models are now becoming harder
to locate, the role of the humble webcam now being usurped by more
expensive and dedicated planetary imaging cameras. To control and use
a webcam, it must be connected to a computer which, for portability, is
normally a laptop.
Planetary Imaging Cameras (High-Frame-Rate Cameras)
Despite their name, as well as being able to take pictures of the brighter
planets, planetary imaging cameras can also be used to image the Moon
and, when a suitable filter is fitted, the Sun.
[5] A dedicated planetary imaging camera. [6] A cooled astronomical CCD camera.
5 67 7Astronomy with your camera