(Click to enlarge)
With the full Moon up and impacted all my program targets I decided to pull out the ZWO EOS adapter I'd bought ages ago and try it with my Canon 100mm f/2.8 Macro lens. I used a mask with a 29.4mm opening on the end of the lens to approximate f/3.3. I tried with it wide open at f/2.8 and had really unattractive flaring stars. The mask seemed to control that mostly.