I didn't spend much time on testing last night. The sky was was clear, but seeing was poor. I put the Nikon D750 on the tracker and took a batch of 30 second exposures around 11pm--48 of them, with the tree in the frame. (I cropped some of it out, as well as the edges). Stacked them in DeepSkyStacker and did some processing in PhotoshopCC.
Here's the test in progress, with the Nikon D750 on the tracker and the electronics--arduino and A4988 controller--on the board below, taken with my iPhone.