I got this Hero 3 Black off eBay. It had a very fuzzy picture. I assumed it was the lens. The lens housing on the midframe was sliced off as seen in the picture. I thought that the lens got bumped or hurt. I ordered a new midframe and lens from iFixit.
Repair was scary. Removing the LCD and power button was very tricky. I advise everyone to go slow. Don't rush it.
I found that that the old midframe was cut away for a reason. The cutaway exposes the lens. This allows you to 'focus' the lens. Hero 3 Blacks are famous for their out of focus lenses.