So why would you want to combine multiple raw conversions in one image? There are two main reasons why you might do this, and both will help you to get a well-exposed shot in difficult lighting conditions.
The first is to combine two different conversions, adjusting the exposure of the second to deal with high-contrast lighting – see our image, below.
The effect is similar to using a graduated Neutral Density (ND grad) lens filter to darken the top half of your image, but you have much more control over the transition between the two exposures.
You can also combine two raw conversions saved with different white balance settings, which allows you to warm up or cool down different areas, rather than the image as a whole.
Combine raw files for a perfect exposure
01 Duplicate your image
To save time when making your adjustments it’s best to create a duplicate of your raw file. This way you can make individual adjustments to each file, rather than opening and adjusting the same image twice.
02 Open in Adobe Camera Raw
Select both raw files by holding the Ctrl button and clicking on both, and then open them in ACR. This should be the default action, but you can also right-click and choose the Open in Camera Raw option.
03 Adjust your images
Now you can make the different adjustments for each image. For our shot we chose a cooler white balance for the first image, which we used for the sky, and a warmer one for the foreground in the second image.
04 Adjust the exposure
For the second image, where we wanted to bring out detail in the rocks, we used the Exposure slider to lighten the image a little, then used the Fill Light adjustment to lighten the rocks and sea.
05 Layer your shots
Now select both images and open them in the Edit window. Select the light image (Ctrl+A) and copy (Ctrl+C) and paste it (Ctrl+V) onto the dark one. Make sure the top layer is selected by clicking on it, then click on the Add Layer Mask icon at the bottom of the Layers palette.
06 Mask out the sky
Using a soft round brush, make sure that the foreground colour is set to black and the Opacity is set to around 25%. Paint over the sky to mask out the lighter image and reveal the darker sky below, and any other areas you want to darken. Remember, don’t get carried away…