Re: picture quality Z7 II vs Sony A7R 4
The lens is more important for image quality than the camera/sensor, especially if we're talking about sharpness which is almost entirely determined by the lens.
The photographer is more important than the lens. Many of us spend years saving up for a f2.8 zoom, we finally get it, and quickly learn that it doesn't improve our photography. Sharpness is also determined by using the correct depth of field, shutter speed, and lighting.
Think of all the old blurry photos (for whatever reason) and videos we easily tolerate because they captured the moment. Especially in photo journalism. I was chatting with a photographer who recently attended a work shop. Their main takeaway was the question: What is more important to you, focus or lighting?
The answer was that inexperienced photographers choose focus and more experienced photographers chose lighting. I'm going through this transition because as we age, our eye site suffers, and we spend less time at 200%. Also, how sharp are the most valuable paintings and artwork? I recall someone earning a lot of fame with some Polaroids. Check out some of the results from smartphone photo contests too.
However, the mirrorless focusing experience is MUCH better with faster glass than slower glass. The F4S glass balances this out for me best because I came over from pro DX cameras. My photography has improved, but I'm still mixed on the experience. Each brand has features I preferred over the other's.
The photographer is obviously the most important thing of all when it comes to photography I was just talking about the gear now, though. It is however of course up to the photographer to utilize the full potential of the gear.
And when it comes to how important sharpness is it depends on several things like the photo in question and how you view it. For some photos or situations sharpness might not be very important at all. It all depends on what result you want to achieve.