Why doesn't pixel peeping with magnified Live View give the sharpest possible image?

Question

I've seen this comment (most recently in this question), or similar, in several answers here on photo.SE: "Pixel peeped images aren't likely to look sharp".

Why is that? It would seem to me that if you go into Live View, full magnification, and then manually focus on the area of interest, then that is as sharp as it is going to get. Of course, one must assume a stationary subject here, and you have to choose you area of interest carefully, but I keep seeing comments like that one which really imply that I'm missing something here.

So why doesn't pixel peeping with magnified Live View give the sharpest possible image?

Answer 1

You're misunderstanding the statement. "Pixel-peeping" during focusing is indeed a good way to get a sharp image. The statement "Pixel peeped images aren't likely to look sharp" means that the image won't look that sharp while you're doing the "peeping" because the viewing magnification is so high.

Answer 2

Simple: live view has to do RAW conversion on the fly. Since that's compute-intensive, especially if sophisticated algorithms which include sharpening are used, live view doesn't give you the final look.

Secondarily, pixel peeping in general often is examining at a level of detail beyond what is important for real printing or viewing, and so gives a view of "non-important" blur — like the denoising artifacts common on point and shoot cameras. I don't think that's your question here exactly but it still may be relevant if you're pushing the effective tolerances of your equipment.