My second mosaic dragonfly in September; actually my second ever and my first in Michigan. My photo views are limited, but I had help from Darrin O'Brien to clinch the identification.
Above and below: later in the morning I found this mating pair and it was actually the photo below from which Darrin was able to make the ID.
Lance-tipped Darner (Aeshna constricta)
I found the email comments from Darrin below helpful. Just goes to show how tricky dragonflies can be to identify and how careful one must be.
The male claspers are paddle-shaped which eliminates some of the more confusing Aeshnas. This would be much easier to see with a side view.
The pattern at the top of the hind area of the thorax would lead me to believe it's a Lance-tipped Darner (A. constricta).
The abdomen is also constricted, but I don't always find this helpful.
Many times a side view of the thorax is best for ID, but this isn't foolproof. In this case, if you have a side view of the thoracic stripes, it should clinch the ID.
With many dragonflies, even dorsal, lateral, and ventral photos aren't enough for ID.
I found these Lance-tipped Darner's at Lake St. Clair Metropark along the path between the nature center and the boardwalk area on Sunday, September 10th while leading a DAS birding trip there. They seemed numerous flying over the path at the start of the walk around 8:15 am - 9:00 am. When the walk ended around 11:30 am or so, I went back and saw hardly anything. This is when the mating pair showed up and perched.