In some implementations a mountable afocal adaptor for a camera includes an attachment plate affixed to the front of a camera housing of a camera and an afocal optical module. The afocal optical module is configured to convert a received optical image to a converted optical image for use by the camera. The afocal adaptor also includes a rotation mechanism with a rotation ring and a wave spring clamp, the rotation ring affixed to the attachment plate and the wave spring clamp affixed to the afocal optical module. The rotation ring and wave spring clamp are mounted relative to each other to rotate around a rotational axis aligned with an axis of an optical path formed between the afocal optical module and the attachment plate and aligned with a view axis of the camera. The rotation mechanism also permits rotation of the camera housing around the rotational axis relative to the afocal optical module.