How To Merge Two Exposures

Photo by Steve Berardi

Photo by Steve Berardi

One of the most common problems in landscape photography occurs when photographing a sunrise or sunset: the sky is always super bright and the foreground is always super dark. This causes some trouble for your camera because it can’t handle that dramatic range of brightness.

There’s a few ways to solve this problem, but one solution is to shoot two exposures: one exposed for the sky and one exposed for the foreground. Then, you can merge these exposures later in Photoshop.

Here are some details on how to accomplish this:

How to get the two exposures

The simplest part is shooting the two exposures. Since we’ll be merging the two exposures, it’s very important to use a tripod here (so both exposures cover the exact same area). This method also works best when there’s a clear line of separation between the sky and foreground.

The first shot should be exposed for the sky. You want to make sure you capture all the beautiful colors in the sky, so keep an eye on your histogram and make sure you don’t overexpose any of your highlights (especially in the red channel)! In this shot, don’t worry if your foreground is completely black (or just really dark), because you’ll be combining this shot with another one. Here’s an example of what this first exposure might look like:

Sky / Photo by Steve Berardi

Sky / Photo by Steve Berardi

For the second shot, you want to expose for the darker part of your image (the foreground). This will usually require a much longer exposure, so keep making your shutter speed longer until the histogram shows that you’ve accurately captured the colors of the foreground. For this shot, the sky might be completely blown out, but don’t worry (just remind yourself that you’re merging two exposures!). Here’s an example of what your second shot might look like:

Foreground / Photo by Steve Berardi

Foreground / Photo by Steve Berardi

How to merge the exposures in Photoshop

In order to merge these two exposures, we’ll use layer masks in Photoshop. Layer masks are helpful because they allow you to control the transparency of pixels in a layer (so you can make pixels gradually go from completely opaque to completely transparent). They’re great for any kind of merging. Anyway, here’s how to do it:

1. Open both images in Photoshop

2. Copy the “sky image” (the one exposed for the sky) and paste it on top of the foreground image. So, you should now have an image with two layers: the background should be your “foreground image” and then there should be another layer on top of that with your “sky image”

3. Add a layer mask to your sky image by first selecting the layer in the layers window, and then pressing the “Add layer mask” button (see screenshot on right). This layer mask will allow you to control what parts of your sky image will be transparent, and which parts will be opaque.

4. Select the layer mask in the layers window, and then select the gradient tool

5. Modify the gradient so it’s linear and goes from black to white

6. Draw a gradient on the layer mask, starting at the top of your image near the sky and dragging it to where the sky meets your dark foreground. This should create a nice merge between your sky and foreground. You’ll probably have to experiment a bit here to get it perfect, and you may have to go in close with a paintbrush tool to smooth out the edges, but this should give you the basic idea.

7. After experimenting a little, here’s the final version of this merged image:

Mojave Desert / Photo by Steve Berardi

Mojave Desert / Photo by Steve Berardi

Other solutions

This method works best for images that have a clear separation between the sky and foreground. So, for other shots where you have dark objects extending into the sky, you might be better off with trying another method (such as HDR or exposure fusion, which we’ll discuss in future PN posts!).

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steveb2About the Author: Steve Berardi is a naturalist, photographer, software engineer, and founder of PhotoNaturalist. You can usually find him hiking in the beautiful mountains and deserts of southern California.

Comments

  1. This could have been a lot better if it hadn’t assumed viewer knew their way around PS (or Elements) already. As it is, it’s just a reminder. If expanded to all the steps required, it could then be a real tutorial.

  2. Steve-thanks for the great articles. As a former film user & now digital guy, I need all the help I can get. For example, one question I have is “How does one do separate meter readings for sky & foreground with an in-camera meter?” Especially since the camera is on tripod and the photos need to be perfectly lined up. I assume you’ll mention a hand-held meter. Wouldn’t it be more cost effective and easier to use a graduated ND filter to take one shot, or to use a camera’s HDR function (if available)? Thanks, Bill

  3. Paul harding says:

    I would not even know , or understand how to open a photo editing program, let alone try and figure out how to use it. i also don’t understand what paste means.
    I am a senior with lousy computer skills and have purchased several “novice/beginner” edit programs but i can’t even load an image let alone try to edit it.

    How come the world assumes we are all computer whiz kids ?

  4. Steve Berardi ;
    MERRY CHRISTMAS AND HAPPY NEW YEAR
    HAVE A NICE DAY, SO CONGRATULATIONS YOUR TALENT IN PUBLICATIONS

  5. @Paul
    It is a problem that photoshop is so hard to use and those that do use it forget that many of us have no clue how to even get to step one. For $200 a year or $25 a month you could try Kelby Training, there is also Creative Live and Linda.com. For free look for MGD 111 – Photoshop I by Jay Shaffer, it is best through iTunes, if you have it, because the latest version is covered there. If you are using Elements, I did not have a lot of luck finding any instruction for that without paying for some Kelby Training courses.

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