[skychart-discussion] Finder circle for DSLR camera

[crayonharry]

I want to make a field of view indicator so I can use my Canon 40D (on a 
tripod, not through a scope)  for astrophotgraphy. i want to be able to show 
the camera's field of view on the sky chart so i can see what area the camera 
is taking in.
I have a 55mm lens and a 200mm lens.
How can I do this?
Many thanks