I can’t tell you how many times I’ve been saved by this little trick I’m about to show you. Sometimes you just don’t get the right exposure on both your background and foreground but the shot is amazing, so, you want to do what you can to salvage it. Here’s how:
1. You open your photo in Camera Raw (ideally, it would be on RAW format, but JPEG works too.) As you can see here, if I expose it correctly for the foreground (my two lovely subjects), the sky is completely overexposed, burnt, gone. So, what we need to do is go ahead and expose for the foreground and open the picture as an object. Just press and hold the Shift key and the Open Image button will switch to Open Object. By doing this, we can later create a second layer that is completely separate and choose the correct exposure for the sky alone, without one layer being linked to the other.
2. Now we create that second layer I was talking about by going to Layer, Smart Objects and choosing New Smart Object via Copy. A second layer should appear on your Layers box. Double click on the thumbnail of your new layer and Camera Raw will be launched again.
3. This time, we expose taking only the sky into consideration. The foreground will be way dark. Click OK when you are pleased with the sky exposure.
4. Now we’ll blend both of these versions of your picture by using a layer mask. Go to Layers panel then you press and hold the Alt (or Option) key and click on the Add Layer Mask icon at the bottom of the Layers box. Now we select the sky that is overexposed with Selection tool (I do this to make sure I don’t accidentally go over to the part of the picture that is already well exposed) and then simply Brush over and you will bring out the sky that had been lost.
5. Now all that’s left is flattening the image and you are ready to save!