http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=38967853
This picture is quite good, although not yet astonishing, I think:-
(Click to Expand)
And also test shots from another user:-
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=39027192
(Click to Expand)
The second picture shows quite clearly that the O-GPS1's astro-tracking function is in action. Just note the locus of the blurred tree and leaves. It seems that the O-GPS1 works good enough for this slow motion application, or at least for those web-sized photos as shown.
Nonetheless, this example shot by a Japanese user does demonstrate some blur, when the picture is viewed at full size:-
(Click to Expand; Warning: Large File; URL: http://pentax.photoble.net/?exif=110802006)
As for the setting up of the unit for astro-tracking, see this previous brief tutorial by the first poster above:-
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=38927268
Last but not least, if you find that this Pentax unit is just a bit too expensive but you still want to shoot the night sky in tracking manner, here is the cheap DIY solution, for example:-
http://www.flickr.com/photos/snapify/2895746095/
And here is the result:-
(Above: The Milky Way; URL: http://www.flickr.com/photos/snapify/2895789493/)
Wow, what a really nice photo!
I actually made a similar DIY equatorial mount before about twenty years ago and I can also confirm that it does work! Do note that the inclination/elevation angle of the mounting base is based on the latitude of the geographical location of where you are. And of course, if you are at the Northern Earth, you have to point the hinge (which facilitate the rotational movement) to the Sky North and ditto if you are located at the Southern Earth, you have to point it to the Sky South.
Besides, I just wonder if the O-GPS1 astro-tracer/tracker can help in making better super-tele moon shots when shooting in very long focal length, as the moon is always moving fast across the frame in that case (that can be seen through the viewfinder during shooting), which would result in some small blur in the final photos that is particularly noticeable when looking at the pictures closer. :-(