The zoomlock is a unique feature on this zoom. The lock can hold the zoom ring at several pre-set locations in the zoom range. but not any position across the zoom course.
This Macro Zoom lens can be found with various lens mounts.
Hold the lock switch backward, and mover the zoom ring. When hear a click, release the switch to lock. To unlock, push the switch forward and move the zoom ring.
This body comes with a self-timer, shutter speed up to 1/2000 and flash sync speed up to 1/125. Vivitar V3000 appears to be a color variety, with chrome top and bottom plates.