How to focus the Raspberry Pi camera lens without breaking it
The Raspberry Pi camera is designed to offer a fixed focus, but it is possible to have limited manual control over the camera focus if you’re very careful.
While the Raspberry Pi Foundation has their own guide on the process, we found George Wang’s video a very straightforward and less invasive way of doing it. Since you’re effectively breaking a glue seal, you will ultimately damage the plastic on the camera module, but as long as you’re gentle and avoid the lens itself the camera will be fine. Bear in mind that the camera module is stuck to the board with tape, so you’ll need to carefully hold it in place as you work the lens glue free.
Just remember – don’t over-turn the lens in either direction less you want it to thread or fall out completely!