Notebook cameras are usually focused for a distance of about 50cm so they are sharp for video phone calls. On a surveillance cam you may like to focus for a bigger distance. Because the lenses are very small and the focus depht is quite big, focussing is not necessarily required. However, to get an optimized focus an adjustment leads to a better image.
The lenses, as small as they are have almost a focus adjustment thread, but this is usually fixed with glue. You may often loosen the glue by turning the lens counter-clock-wise. However I had also cameras, where the lense holder ripped completely off. To loosen the almost as a crown shaped lens holder you need actually a special tool. With pliers you probably destroy the camera.
The following procedure helped me to create a simple tool to remove the lens:
- Put a very small piece of paper into the lens opening for protection.
- Heat up a proper piece of plastic on one side until it becomes viscous on the surface.
- Push the molten material onto the lens and let it cool down. Now it has the form of the crown.
- With the cold tool remove the lens first completely and remove the glue rests from the lens thread.
- Now screw the lens in again and focus accordingly.
To set the focus to a longer distance you need to turn in the lens closer to the sensor. If you try to turn in the lens first, you take a high risk to rip off the sensor housing. Therefore first turn left - clean and then turn right. A fixing of the lens with gue is not required (from my point of view). It holds also without !?