|Blending two or more
exposures to create an image with one good exposure
© Rod Barbee
|This is a technique that essentially
increases the dynamic range of your camera by taking two or more exposures,
each optimized for specific elements of the image, and blending them in
Photoshop or Photoshop Elements (or any image editing program capable of
Layers). It's usually used for scenes that have a foreground in shade and a
sunlit background, something that often happens at sunrise or sunset.
First of all, all exposures must be of the exact same composition. This means using a tripod. Though you can do this without a tripod, you'll spend more time in Photoshop lining up the images than it would be worth. So do yourself a favor and use a sturdy tripod.
Determine exposures for each part of the image ahead of time. Don't use
Program Mode or Shutter Priority Mode for this. Only Manual or Aperture
Priority. The Aperture must remain constant, only the shutter speed can
Ok, that's it on the camera side. The hard part is remembering you've done it so you don't simply delete two bad exposures. (I sometimes will stick my hand in a picture either before or after the exposure sequence to remind myself I just did something important)
In the computer
Once you get the images downloaded to the computer, open your image editing program. I'm going to base this tutorial on using Photoshop or Photoshop Elements.
Open both images and place them side by side. Click on the Move Tool.
In Photoshop it now looks like you have the same two images showing on
the desktop. You may close the one you dragged from if you like.
Ok. So now you have one picture on top of the other. Now is where the
magic of Layers is unleashed.
Click on the top layer to make sure it's active. (also make sure the eyeball icon is on so that the layer is visible). Now click on the Erase Tool. Make sure it's at 100% Opacity and that it's a soft brush. Set the size to cover about a quarter of the portion of the top layer that you want to "cut out". You can set brush size, opacity, and hardness or softness from the Options Bar at the top of the Photoshop work are, just below the Menu Bar.
Now click on the left mouse button and start erasing the "bad" part of
the top layer. See what happens? The good exposure on the bottom layer is
revealed. Continue erasing as much as you can without cutting into the "good
exposure" portion of the top layer. Go ahead and decrease the size of the
brush. (Hint: Use the bracket keys next to the "P" key: [ ] . The left
bracket makes brushes smaller, the right bracket makes brushes bigger. You
can also change the softness by holding down the Shift Key while using the
bracket keys. The left bracket causes the brush to be softer edged while the
right bracket makes the brush harder edged.)
This technique works especially well if you're photographing interiors of buildings and still want the windows to be properly exposed. During the day, windows will be way over exposed if you simply expose for the interior. Instead, take two shots. One to get the right exposure for the interior, and another for the window areas. If you don't have a spot meter in your camera, simply walk up to the window and fill the frame with what's outside to determine exposure.
Of course, as with just about everything in Photoshop, there are a number of ways to do this. Try the Erase Tool method first and then try using a Layer Mask on the top layer. Use a black brush to "erase" what you don't want. The cool thing about using a Layer Mask is that if you make a mistake you can fix it simply by painting over your mistake with a white brush, thereby restoring what the mask was hiding.
Layer masks are only available in Photoshop (layer masks are only
available for Adjustment Layers in Elements). First click on the layer in
which you want to apply the mask, then click the Layer Mask Icon in the
This creates the Layer Mask. Click on it to make sure it's active. Choose the Brush Tool and make sure it's black. Now paint on the image where you want to "erase" the bad exposure area. You'll see the layer below being revealed.
Exposed for foreground
Exposed for background
The two exposures blended in Photoshop