Today’s Question: How concerned should I really be about over-sharpening photos in Lightroom [Classic CC]? Doesn’t Lightroom limit the amount of sharpening you can apply, so there isn’t much risk of sharpening too much?
Tim’s Quick Answer: While Lightroom Classic CC does indeed significantly limit the amount of sharpening you can apply to an image (compared to, for example, Photoshop), it is still very easy to apply too much sharpening. When an image is over-sharpened you can see edge halos and other visible artifacts in an image, which detract from the overall appearance of the photo.
More Detail: There are a handful of adjustments that many photographers seem to fall into a trap with, thinking that “if a little is good, a lot must be great”. Sharpening tends to be one of those adjustments, along with saturation and a handful of others.
The primary risk of sharpening an image too much is that there will be visible artifacts. This can be a simple appearance of excessive texture that I refer to as a “crunchy” appearance. Another common side effect of sharpening that is too aggressive is the appearance of bright halos along contrast edges within the photo.
In general it is the size of the sharpening effect that is most critical when it comes to visible artifacts. As a general rule, a value between around 0.6 and 1.0 works well for typical photographic images. Higher values should generally only be used with images that don’t contain much fine texture.
The Amount setting determines the overall strength of the sharpening effect, and generally a value ranging between about 50 and 75 works well, depending on the image. Going much higher, especially if the Radius is set above 1.0, will increase the risk of visible artifacts in the image.
So while Lightroom does limit the degree of sharpening you can apply in the Develop module compared to what is possible with other tools, there is still a risk of visible artifacts in the image if you apply settings that are too aggressive.