This is an easy trick to make your gopro focus from almost 2x shorter distance.
Things you may need;
- A dremel tool with pvc cutting blade
- A glue gun
- Bottle cap from an air-wick electric air freshener
- Lens from a cheap led headlight (most of them use plano-convex lenses, make sure the lens you use looks same as on picture)
Cut the cap as seen on picture and glue lens to top.
Attach the cap on gopro lens and done... (You can use same lens to take closeup pictures with your phone cameras etc. too, works very well.