Hi Steve,
When using camera in prime focus, there is no such thing as "magnification".
Instead, there is "scale", expressed in "/pixel or pixels/" or pixels/deg.
What you really want to ask is "how big field of view I will have when I attach the camera?"
This will depend on focal lens of your telescope and the linear size of the camera sensor.
The formula is alpha=2*atan(d/(2*L)), where
alpha is field of view expressed in radians (if you want degrees, you have to multiply this by 180/pi)
d is linear dimension of sensor in mm
L is focal length in mm
