All makes sense as to what you are saying. I actually missed reading the part in your posting of your estimate for clear focus at 30 cm. I did see the 8 cm figure and wondered if perhaps lens was not distanced correctly (threaded in too far?). It would be nice to know an actual official figure from SJCAM. Perhaps not a critical setting as most users not concerned whether it's 3 inches or 3 feet. In fairness I may not have the settings correct on the SJ8 for inside shooting. Side by side with the "real" 4K Thieye , the SJ8 didn't seem to match even on the more distant objects. Comparison Screen grabs in previous post. I think what Sauron and I both were disappointed about, was that we expected to obtain similar results in comparison to the cameras we previously used for nature closeups. I have used a LightDow 4000, LightDow 4K ultra HD, Apeman 4K, and Thieye T5edge "true"4K. All of these cameras are ultra wideangle and are in focus under 15 cm. I had a quick chance to set SJ8 on tripod next to stump with some peanuts. After letting it record about 30 minutes I only had wasted footage of blurry birds. I have a screen grab from the video. I am thinking lens was about a foot away. As I look at the more distant objects you are probably correct in saying the lens is ok.