Hi. Newbie hobbyist who started last June. Does anybody know what would cause the "bullseye" in the center of this shot? I shot this using an a7r iii with FE 2.8/24-70 GM lens. My settings were 15 sec, f/4, iso 800. Also, I didn't see the bullseye on shots at 5 sec, f/4, iso 800. I had Long Exposure NR off for both shots. Thanks.