Pentax O-GPS1 GPS Unit
Note: I am not an experienced astrophotographer and live near to Toronto, Ontario where there is a lot of light pollution. I was able to take some photos from my backyard and others in a lake front park where looking out to the lake was fairly dark but turning around 180 degrees put strong street lights in your face.
The two lenses I used were my Tamron 28-300mm F3.5-6.3 and an old Lentar 400mm M42.
At this point I can describe Pentax backwards-compatibility in two words: it works! (In this case we have a new camera with a very new O-GPS1 unit using a very old lens)
Below are some sample star photographs taken with the help of the O-GPS1. Click on any photo to enlarge it.