The difference is quite distinct, I always thought my lens was focussed too close, despite somebody on here insisting that if you focus at 6" everything will be in focus, that was clearly not the case.Here is an example of the difference between sharp and acceptably sharp. I am planning on changing the lens on my GoPro 3+ to the Peau Productions 3.97 mm one. I was always happy with the sharpness of the existing lens but wanted a narrower field of view and less fisheye. My new lens should arrive soon but in the meantime, I loosened the old lens and tried refocusing it to see if there would be any improvement. You can easily see the difference. The original setting on the left and refocused on the right. These are 100% crops from the full size and were taken about a minute apart.View attachment 1730
Using a hyperfocal distance close to the camera will give an acceptably sharp image at a distance, but if most of what you are shooting is at a certain distance, then you should focus at that distance for maximum sharpness. Objects which are 6" from the camera may be out of focus now, but I will never have my copter that close to something.