Originally posted by hjw I do both, I have the O-GPS1 for tracking and than stack about 20 pictures of 10 seconds each. I am new to this too and I am still experimenting with conditions. I think at 300mm the O-GPS1 has found its limits.
I think when you start getting up towards 300mm you need both an extremely stable mount plus luck of the draw in not having anything to throw off the O-GPS's tracking in the surrounding geography.
I went out a couple nights ago with the camera mounted on my tripod and do what I would I couldn't avoid trailing, even at short 10/20/30 second exposures. I suspect its because my location sits where a mill used to be and the ground is pretty much thin soil over an insane amount of iron slag.
When I went out a few weeks ago and realized I'd forgotten my tripod mount I was forced to use a rock and my hat to prop the camera up with and I pulled off this shot at 300mm and 60 seconds (basically the max duration for the tracker, pulled back by 10 seconds).