I was looking through a forum discussion recently and came across the ubiquitous "can you see the difference?" type of post. My answer is almost always "yes." Your answer may vary. ;~)
I've written about "good enough" before, but I realize that I haven't pointed out the real problem with "good enough": it's a time-sensitive, subjective analysis based solely upon how well trained and experienced you are. Moreover, since we're talking about seeing things with our eyes, your eyesight also comes into play.
As my ophthalmologist will tell you, I'm a stickler for prescriptions. She spends way more time dialing in my eyesight than she does with any of her other patients, and we discuss things that rarely come up with other patients, like CYL (which tells you about astigmatism). Now that I've had cataract surgery on both eyes corrected to distance, that means that I use three different sets of prescription "readers", depending upon what device/page I'm reading. I don't want "good enough" sharpness, I want "best possible sharpness." Using a +1.5 diopter change when I should be using a +1.75 one doesn't cut it for me. (I also dislike the pincushion distortion that all off-the-shelf readers impart, but that's not a problem with acutance, the thing I'm writing about today.)
I've been lucky enough to have trained with a number of pixel peeping processing perfectionists over the years, and that has instructed me as to what to look for, something I practice pretty much every day. I also use tools to help me. I have one plug-in that allows me to view four different sharpening conditions simultaneously that I've set up so that it helps me see the difference in missed focus, motion, lack of depth of field, etc.
But let's get back to the "good enough" problem. Simply put, your evaluation of "good enough" is randomly different than not only mine, but everyone else's. That's because what you can see, what you've been trained to see, and what you'll overlook is different than everyone else.
Moreover, your "good enough" bar will change over time. If you've been using digital cameras as long as I have (now 35 years), you'll immediately know that the "good enough" bar has moved and moved and moved and moved. If you've ever pulled up an older image you took that you thought was pretty good and said "why didn't I see that?" you know what I mean.
Be careful with declaring something "good enough." This is essentially saying that it probably has flaws, but you either can't see them or will ignore them. Be careful when reading someone else who says something is "good enough." You know nothing about how well trained they and what they can and can't see, let alone what they're willing to ignore. But it goes further than that: beyond "good enough" is "best." The same problems occur when someone says product X is the "best", particularly when it comes to anything regarding image quality.
This is one reason why I've long been an advocate of "collect optimal data, process data optimally." I've never found that there isn't a better "optimal" I can reach for, even with my current gear. Whether that means more sampling (more pixels), more accurate focus (better edge clarity), better product handling, or anything else doesn't matter: I've pretty much always found that if I consider my current "optimal" as a placeholder until I figure out what is better might be, I stay at the forefront of what can be done in photography.
