Coupling the camera to the scope
The afocal method Is mounting
your camera to the eyepiece.
Then focus the telescope
through the camera lens. The  
object becomes increasingly
dimmer having to go through all
that glass. This is the least
desirable way to photograph. All
kinds of things could go wrong.
Here I have one camera mounted
piggyback and the other to the 5"
scope for prime focus photography.
The cables coming out of the
cameras are the shutter
lock-and-release cables needed for  
long exposures to help eliminate  
vibration.
The piggyback method is nothing more
than mounting a camera somewhere on
the scope or mount and using the mount's
drive to track the stars. Use this method to
get those wide-field photographs.
Place an eyepiece inside the adapter
tube to increase the magnification.
Then you can increase the
magnification more by extending the
length of the camera adapter tube.
Prime focus photography is by far the most
popular method used. Basically, attach the
camera to the focus tube and use the
telescope as a gigantic telephoto lens. The
varimagni (the variable magnification finder)
shown in this photo is used to magnify the
image on the camera's focus screen.
O-M1 camera with the  lens removed
and replaced with the camera
adapter.
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