I'm far from expert, but I think that having skills in sharpening can play a big part in the final result, but the benefit and the approach required vary depending upon a number of factors. e.g. :
- How sharp the shot is to begin with
- How noisy the shot is to begin with
- How much fine detail is present
- How much cropping is required
- Pixel size of sensor
- Output size
- Output medium
- Aesthetic goals
Within Lightroom I find one of the most valuable controls to be the Edge Masking slider, which adjusts whereabouts in an image the sharpening is applied. This control can be used to limit sharpening effects to only high contrast boundaries - i.e. edges - and avoid plain/smooth areas for which sharpening is neither desired nor welcome - such as the sky - especially if the picture is noisy. Once you have targeted the areas to be sharpened you may find that you can apply a little more sharpening than usual to get the edges to crispen up nicely. However, you need to be careful not to go overboard and end up with halos around your subject - a technique favoured by some, but which I find ugly.
The sharpening adjustments should be applied when viewing at 100%, because any other size is not an accurate representation of the changes being applied. Once you have the image looking good at 100% within Lightroom you need to turn your attention to producing the final output. When you export files there is an additional sharpening option to be considered - Output Sharpening. Assuming that you are outputting for web use then probably you will be resizing your image to make it smaller. In so doing much of that fine detail you so studiously massaged and refined at 100% is suddenly going to get squeezed into a far smaller space and a lot of it will be consumed and destroyed. That's fine, but you need to consider applying some output sharpening as the last step before saving so that you can restore some pop back into the shrunken image. I don't print, so I usually have Output Sharpening set to Standard for Screen and leave it like that.
For an image which is sharp to begin with and yet is only going to be viewed at small sizes you may find it a waste of time to bother sharpening within Lightroom as the details will disappear when you resize. For such images Output Sharpening alone may well be enough. On the other hand, if you are going to be making massive crops, maybe even 100%, for final output then it may pay dividends to fine tune sharpening within Lightroom before you export for print or web.
Here is an example of some fine tuning within Lightroom at 100%. The subject is so small in the frame that 100% use would not be unrealistic, so I think it's worth putting in the effort if the image is to be used at all. For this example I started by adjusting the Edge Masking, because I did not wish any sharpening to be applied to the sky or smooth surfaces of the aircraft. Then it was a question of tweaking the other sliders until I was satisfied. It's worth a note that after sharpening the image was still a little flat so I also ramped up the Clarity slider just a bit, to deepen the blacks and add some highlight sparkle.
Unfortunately I think the JPEG screen print has slightly compromised the comparison here, but the improvement is still visible....
If we look at the final output (cropped and resized to 50%) before and after the sharpening (both have output sharpening applied) the difference is still there and quite clear to see.
As shot :
With additional Lightroom sharpening and some clarity :
