Luminosity masks are of course enormously popular for exposure blending and dodging and burning. But that’s really just the tip of the iceberg. You can use luminosity masks for a huge range of creative post-processing techniques, including “focal length blending”.
Focal length blending involves combining two or more images shot using different focal lengths. Sounds bizarre or impossible, but it’s an incredible way to captures landscapes that you simply cannot capture in one frame. For example, you may run into a scene where the foreground requires a wide-angle lens to get great leading lines while the background requires a longer focal length to keep from looking tiny. That’s exactly the scenario I was facing when I shot the image below and shot at 16mm to capture the gorgeous waves and then zoomed to 35mm to capture the sea stack large enough to show its glory.
The techniques used here should feel somewhat familiar if you already understand exposure blending. You paint through luminosity selections to create a mask that reveals one layer on top of another. In this case, to reveal the 35mm sea stack on top of the 16mm image. There are of course additional considerations. You’ll need to align your images before blending. And a credible blend may require some additional creative work.
The trickiest and most unique part of this blend is the reflection. You have to create it. You can’t use the 16mm reflection because it’s too small. And you can’t use the 35mm reflection because it doesn’t match the image at all. The key is recognizing that the reflection is basically appearing as a dark pixels in the shadows of the foreground. So we can create create a fake reflection using a fill layer and luminosity selection.