It's called field rotation, and yes, it's normal and expected. This is why you have to polar mount a telescope to do long exposure photography; viewing objects in an altitude-azimuth way shows field rotation. You can see this in constellations too; Orion looks like he's resting on his right side (our left) as he rises and he looks like he's resting on his left side (our right) as he sets.


Can you give a link where this information can be found?

No, I want to know where Astronut got his info.

15 years of experience in astronomy and 10 years of experience doing astrophotography. I'm planning on doing a video comparison time lapse of the moon with a polar mounted telescope and with an altitude-azimuth telescope. What you'll see is that the altitude-azimuth mounted telescope shows rotation while the polar mounted one does not. I was going to do that a couple weeks ago but ended up not having the time.