A Cass County jury also found James Heidenreich of Dowagiac guilty of eavesdropping, possession of child sexually abusive material, manufacture of marijuana and gun charges.
He faces a Feb. 1 sentencing.
Heidenreich's girlfriend discovered the video in his jacket. It showed a 17-year-old family friend taking off her clothing before using a shower in Heidenreich's bathroom.
Police found marijuana plants and guns in July while searching Heidenreich's home and property, about 70 miles southwest of Grand Rapids.
Heidenreich had testified the camera was not set up to secretly videotape the teen. He also denied growing the marijuana.