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Astrophotography has come a long way since the idea of attaching a camera to a telescope was formed.

Film Photography

Early History
The birth of the age of photography was at the first public announcement of
Louis Daguerre's process, in January of 1839, when the Daguerrotype became
available to the world.  The speech was given by Francois Arago, who combined
careers as an astronomer and a politician, and was an early supporter of Daguerre.  
Months before this announcement, Daguerre had made a photograph of the moon
at the request of Arago, producing a clear impression, by 1838 standards.  It seems
that astrophotography preceded photography, which is reflected today by astro-
CCD imaging arriving before snapshot CCD imaging.

The daguerreotype is an early type of photograph in which the image is exposed directly onto a mirror-polished surface of silver bearing a coating of silver halide particles deposited by iodine vapor. In later developments bromine and chlorine vapors were also used, resulting in shorter exposure times. Unlike later photographic processes that supplanted it, the daguerreotype is a direct positive image-making process with
no "negative" original.

Film astrophotography is a very cost effective and satisfying way to take simple astrophotographs, using a camera on a piggyback mount (on top of a polar aligned scope, for instance).  With the use of a relatively wide angle lens (28-50mm), exposures in the range of 5-15 minutes each can result in very pleasing photos of constellations and the Milky Way, and they are more forgiving of slight inaccuracies in  polar alignment and guiding.

The introductionof the SLR (single lens reflex) camera made the introduction of amatuer astrophotography a real possibility.
Soon all maner of attachments were in production for the connection of this type of camera to the amatuer telescope. a second hand SLR camera is relatively cheap to purchase and can be easily attached to your telescope. Films are getting harder to obtain and few places process these films but it is available to those interested.

Cameras were attached to the telescopes in two methods, piggyback and prime focus.

The piggyback involved using the tripod thread in the base of the camera to attach to the tube rings that hold the tleescope to the mount. The observer could then use the telescope to track a small area of the sky thus keeping the camera fixed on the same point of the rotating sky.

The prime focus method is a more complex method of attaching the camera on the focuser with or without an eyepiece. A threaded attachment or 'T' ring is used on the camera and inserted directly where the eyepice goes. A second piece of equipment called a flip mirror is used with an eyepiece to set the direction of the telescope. This method requires an accurate alignment of the celestial pole and suitable motor drive equipment as the use of the eyepiece is not possible during the exposure. An alternative to the drive motors and flip mirrors is to piggyback a guide scope on top of the telescope and view the sky through this second scope.

In either type of set up the use of motors is a preferred option to the slow motion controls at low power and a definate
requirement for extended exposures or medium to high power magnifications.

Specialised films were soon developed to make the most of the low light requirements of astrophotography.
The main problem film makers realised is that moisture causes the reaction of light on the film to be reduced, so
new techniques were developed including the 'baking' of films to reduce the mosture. This resulted in much fainter
objects no longer being washed out by the slow exposure to light.

Digital Photography

Digital cameras are now so common that even a large number of professionals use them in preferance to the 35mm film cameras.

There are many types of cameras and attachments to make the most of your telescope viewing. Significant changes to technology now mean for an amatuer the possibility of a great shot is at your fingertips or key board.

Firstly there is a greater outlay for the equipment than with film but you can see exactly what you get in a an instant, or in a short while when the computer has finished. The digital camera can be attached to the telescope in the same manner as the SLR  but the compact digital requires to see through the eyepiece to get the picture.

If you choose to buy a dedicated astroimager then the set up is easier as the imager goes directly  into the focuser but in doing this the magnification is limited by the 'F' ratio of your scope and what barlows you choose to use.

This is where the cost increases. A dedicated astroimager requires a direct conection to a computer, the required software to run and process the image, and, a reasonable motor drive and accurate polar setup.

So even a cheap laptop, simple astroimager and the motor drive for you scope you can be in the $2,500 price range. From the people I have spoken to the imagers are equal to a 6mm eyepiece.

On my 200mm F4 scope that is a magnification of 132x with a field of view of a third of 1 degree (20 arc sec). A photo of the moon when full would require to be made of a mosaic of between 9 and 16 individual photos, depending on the resolution. To incease you magnification you will need a good quality barlow or the image will be distorted around the edges.

Once you have the basics there is no extra costs except for printing of your images at your favourite retailer.
The advantage that digital has over film is that you can take dozens of shots and only print what you like, with film you don't know what is a good shot until it is printed.

Some software is freeware of the internet and is dedicated for astrophotography. You can try out Registax-V4 for free.