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Hi Nortilus
For long exposure astrophotography (say greater that 2 or 3 mins) at long focal lengths (say 1000mm +), your mount will need to be polar aligned and capable of auto guiding.
Tracking is where the mount simply tracks the object at a standard rate, usually the sidereal rate, to compensate for the Earth's rotation. This can be achieved in an Alt Az mount as well as an Equatorial Mount for visual observing. For astrophotography, you will require an equatorial mount, accurately polar aligned, that is also capable of auto guiding.
Auto guiding is where the tracking of the mount receives feedback to the drive motors, making (hopefully) small adjustments to compensate for small mechanical errors in the gears, poor polar alignment, atmospheric refraction, etc.
Therefore, a mount need not be GoTo, although that helps find objects easily. But, it needs to be a well engineered mount that has low gear errors (periodic error) otherwise you will get trailed stars.
Generally, such a mount will cost over $1500.
Hope that helps
Cheers
Dennis
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