Star Trails

Is it smart to use a 600mm lens to photography stars?
How do you aim this monster?
Is it really in focus? How would you know?
And what you thought was the North Star wasn't.
Was this a waste of good photons?

And if I could only remember the formula for exposure time vs focal length for star movement.

[Kerri]

Beautiful

[Frank Hymus]

:) As regards focus, go to manual and set to infinity I'd say. a nice heavy tripod I;d say. Cool composition anyway.