Originally posted by cdurfor Can anyone explain what concerns are associated with resetting the image sharpness from the "factory setting" to max sharpness? If not, why aren't all cameras set to maximum sharpness?
The word "sharpness" for this parameter is a bit misleading. It would be more accurate to calling it "sharpening" - implying (correctly) that it is done by somewhat "artificially" mucking with an image to give the *appearance* of higher sharpness. There are different algorithms than can be used, and I don't know what Pentax does specifically. But the basic idea is generally to detect edges and to increase contrast around them, so instead of a soft transition from black through gray to white over the course of several pixels, you have a clear line between black and white. And the more of this you do, the more "sharpening artifacts" you will see in cases where it's just black and white. For example, if it's a light gray bordering on a dark gray, the sharpening algorithm may make the edge of the light gray object white, and the edge of the dark gray one black, creating "halos" around objects. How noticeable those halos are will depend on how large you view the image.
So usually it is best to only do any heavy-duty sharpening as the last stage in processing, after you've already decided on an exact print size and can judge what amount of sharpening appears to create the best balance between the appearance of sharpness and the existence of these halos an other artifacts. and that's why the default is to do little of this in camera.