Your photography has been progressing and you've made the leap from shooting in JPEG to Raw. Along with this, you've plunged headlong into Lightroom and all of the editing marvels that it affords you. Plenty of the controls are familiar, after all you've been adjusting the white balance in your iPhone photos since you realised you could stop people looking corpse-blue with a simple slide to the right in Snapseed. A few of the others need a bit more thinking about, but they're essentially the same. And then there's the clarity slider. Clarity? What the blinking heck is that all about?
Before we wade headlong into the ocean of clarity, we need to take a step back and have a quick re-cap of contrast. Contrast is the difference between light and dark in an image. Increase contrast and an image will seem bolder; decrease contrast and it'll have a more muted feel. Adjust the contrast and it has an effect across the entirety of the photo: highlights, shadows, and mid-tones. This is where clarity comes in.
Clarity's influence over contrast happens in the mid-tones of an image; by increasing clarity, you sharpen the edge detail and definition among these tones, leading to a punchier, sharper looking image. Conversely, decrease the clarity value and you'll soften edge detail and lose definition.
Ramping up the examples
The effect that the clarity slider has on your photos is likely as clear as mud until you see it in action. I have, therefore, reproduced the same image but with different clarity adjustments, to see how it looks.
Why, then, would you want to adjust the clarity in your photos? For a start, I've exaggerated the adjustments in my examples to show you precisely the impact it can have. With more subtlety, it can add definition to landscapes, or emphasise a misty, dreamy feel, and give portraits a gentler feel.
These aren't especially thrilling portraits of my cousin, Emma, but they serve the purpose of exploring the clarity slider perfectly.
There's nothing at all wrong with the original image (it's been cropped and white balanced); but look at how Emma's skin appears softer and more even with a -15 point adjustment to clarity. The background hasn't been affected too much, but she looks better for it.
If you'd like to get even more advanced, you can use Lightroom's adjustment brush to paint softer and more even skin with a negative nudge, but bring definition to a portrait subject's hair by selecting that and giving it a positive clarity adjustment. That's what I've done here.
A cautionary conclusion
As with most things, subtlety is the key to clarity. Too much of it in either direction can leave your photos looking more like cartoons or watercolours than you otherwise might want. And you're not going to want to fiddle with the clarity slider on every photo, either. But at least you can have a bit more confidence about what it does and how you can make it work for you now.