How can you tell??

[Scott Frye]

1) How can you tell if the picture is oof at capture time or just needs more sharpening.

2) How can you tell if the blacks or whites are "blown out" -- or there just is no detail in those areas.

[David Thomasson]

1) How can you tell if the picture is oof at capture time or just needs more sharpening.

Sometimes it's both. If a picture is just a little out of focus, sharpening (if you do it right) can repair that to an acceptable level of sharpness. Raw images are inherently a little bit soft, so they almost all need some sharpening. How much? It comes down to a matter of eye and judgment.

2) How can you tell if the blacks or whites are "blown out" -- or there just is no detail in those areas.

Assuming you shoot raw, you can tell in ACR by lowering exposure and watching the right end of the histogram. If lowering exposure doesn't "unclip" the clipped areas, there's no detail in them to recover.

EDIT: I don't know of any way to tell from the LCD screen on the camera. I have to see the image in Photoshop.

[John Chardine]

Scott- Camera systems differ in the amount of magnification you can give an image on the rear LCD screen. Canon allows you to magnify up to a point where the pixels are still not visible (is this 100%??) whereas I know my Nikon D300 at work allows magnification to beyond pixelation. I mention this only to say that to answer your first question depends on the camera maker. It is hard to describe in words but you "just know" when an image is sharp on the LCD. On my 1Dmk4 at full magnification it will still look sharp with maybe just a hint of softness. When you see images at full magnification that are not sharp, the difference between this and a sharp image is stark. I would say, get to know your camera and lenses and find out the best they can produce and use that as a benchmark.