The lens aligner is started, after opening it, from the lever on the left. You can move the hotspot (the red point) in the 5x5 grid. From the - and + buttons you can increase or decrease the black spots on the lens. A black spot can be in three different sizes. Reset button will just start the puzzle from the beginning.
This is the low-spoiler guide for "Strange lens device" puzzle in Call of the Sea. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.