I have the same issue constantly!
Camera buzzes and screen is fuzzy when zooming in. This doesn't matter which mode the camera is in. Anytime we zoom, whether it's a photo or video, it becomes fuzzy and makes a strange buzz sound.
The temporary fix: Shake the phone vertically(while zoomed) to hopefully make the part that sticks, unstuck.
Stupid but it's done this for months but after reading many posts all over seems like it's pointless to ask for a fix.
Samsung are aware of the problem, its a hardware issue, a camera module apparently. I took mine into a Samsung store today showed them the issue and the guys who worked there knew straight away what it was, I asked was it the camera module and they said yes and it will be fixed and returned within 24 to 48hrs, they also gave me a loan phone to use, so was happy with the service I received. I will update this message when I get the phone back.
Issue fixed and phone back already, It was a camera module, the parts they replaced were (M-cam, kit, sub ) the receipt states, but all working perfectly now and was a great turn around time.