This year’s Camden Windjammer Festival weekend concert features Massachusetts-based guitarist and bandleader Johnny A., aflatpicker so remarkable that Gibson designed a signature guitar in his honor, at Camden Opera House, 29 Elm St. Johnny A. will play a solo show, opened by Maine singer-songwriter Caroline Cotter. Tickets are $26 in advance/$34 day-of-show; choose your own reserved seat online/next-best-available assigned at door. Tickets via camdenoperahouse.com or (207) 236-3154. Sponsored by Grand Harbor Inn and 40 Paper.