There are six methods to attach a camera to a telescope for
astrophotography. These are Piggybacking, Direct Coupling at the
telescope's focus, Afocal Positioning of the camera, Positive and
Negative Eyepiece Projection, and Compression Positioning of the camera.
These methods will now be explained.
Piggybacking
This method of attaching a camera to a telescope does not involve the camera actually taking pictures through the telescope. Instead, the camera sits on the telescope and takes a long exposure through its own lens while the telescope tracks the stars. This method can give superb images of comets and the Milky Way Galaxy.
Direct Coupling
This is the easiest way to attach a camera to a telescope. The telescope does not need an eyepiece and the camera does not need a lens. The telescope goes onto the camera. Refracting telescopes, Maksutov-Cassegrain and Schmidt-Cassegrain telescopes work well in this configuration. However, many Newtonian telescopes will not reach focus due to the fact that the image plane is not far enough from the end of the eyepiece tube.
Afocal Attachment
This method will work with any telescope and any camera - even with compact digital cameras and video cameras. This is a very easy method to use and is practically foolproof. The camera lens is set at maximum aperture (that is the lowest f-stop number) and focused at infinity. Do not use autofocus. The camera is then held in place with a bracket or simply placed on its own tripod. A bright object such as the Moon is best for this method as the camera does not track with the telescope. In fact, because the Moon is so bright it is quite easy to simply hand-hold the camera as the exposure will be short.
Positive Eyepiece Projection
This method gives a larger magnification than by Direct Coupling. An eyepiece is attached to the telescope, but the camera, behind it, has its lens removed. The downside of this method is that images tend to be sharp only at the centre, which means this may not be good enough for shots of the Moon. However, on the plus side, positive eyepiece projection will work with any telescope, Newtonians included.
Negative Eyepiece Projection
This method is very similar to Direct Coupling but a teleconverter or a Barlow lens is added for extra magnification. The benefits of this method compared to positive eyepiece projection, is that images of the Moon remain sharp throughout.
Compression Positioning
In this method of attaching a camera to a telescope, a focal reducer (telecompressor) is used. A focal reducer is basically the opposite of a Barlow lens - it has a convex lens to make the image smaller and brighter, reducing the focal length and f-ratio, hence the term compression. This is the method that is often used in deep-sky astrophotography.
Piggybacking
This method of attaching a camera to a telescope does not involve the camera actually taking pictures through the telescope. Instead, the camera sits on the telescope and takes a long exposure through its own lens while the telescope tracks the stars. This method can give superb images of comets and the Milky Way Galaxy.
Direct Coupling
This is the easiest way to attach a camera to a telescope. The telescope does not need an eyepiece and the camera does not need a lens. The telescope goes onto the camera. Refracting telescopes, Maksutov-Cassegrain and Schmidt-Cassegrain telescopes work well in this configuration. However, many Newtonian telescopes will not reach focus due to the fact that the image plane is not far enough from the end of the eyepiece tube.
Afocal Attachment
This method will work with any telescope and any camera - even with compact digital cameras and video cameras. This is a very easy method to use and is practically foolproof. The camera lens is set at maximum aperture (that is the lowest f-stop number) and focused at infinity. Do not use autofocus. The camera is then held in place with a bracket or simply placed on its own tripod. A bright object such as the Moon is best for this method as the camera does not track with the telescope. In fact, because the Moon is so bright it is quite easy to simply hand-hold the camera as the exposure will be short.
Positive Eyepiece Projection
This method gives a larger magnification than by Direct Coupling. An eyepiece is attached to the telescope, but the camera, behind it, has its lens removed. The downside of this method is that images tend to be sharp only at the centre, which means this may not be good enough for shots of the Moon. However, on the plus side, positive eyepiece projection will work with any telescope, Newtonians included.
Negative Eyepiece Projection
This method is very similar to Direct Coupling but a teleconverter or a Barlow lens is added for extra magnification. The benefits of this method compared to positive eyepiece projection, is that images of the Moon remain sharp throughout.
Compression Positioning
In this method of attaching a camera to a telescope, a focal reducer (telecompressor) is used. A focal reducer is basically the opposite of a Barlow lens - it has a convex lens to make the image smaller and brighter, reducing the focal length and f-ratio, hence the term compression. This is the method that is often used in deep-sky astrophotography.
0 comments:
Post a Comment