Jeff Smallwood Photography
When a GND Just Won't Do
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Nov 12, 2012

How To Combine Two Separate Shots

When a Graduated ND Filter Just Won't Do (video below)

Created with a simulated GND in
post-production using two separate shots.


Taking long exposures is one of my favorite techniques. I don't go anywhere without my B+W 1.7 and 3.0 filters and being able to slow things down, even in full sunlight in the middle of the day, can help create some unique situations.

If shooting LE is a favorite technique, seascapes are one of my favorite subjects. Unfortunately there are time when the light is too uneven in a scene. In order to get a long exposure of the water to get it flat and soft and properly exposed, you may end up with a blown-out sky or an exposure of the sky you aren't happy with. The opposite may be true, exposing for the sky may not give you enough time to soften the water.

The shot at the right was such a situation. What you see on the right is the final product, which is made from two separate shots. One I exposed for the water, one I exposed for the sky. Take a look at the two source images below. Both were taken at f/18, ISO 100, at 13mm. However, they were taken with drastically different shutter speeds.

10 seconds
30 seconds

The Problem

As you can see, the image on the left has a well exposed and colorful sky but the water could be brighter and softer (at least that's what I was going for). The image on the left has softer and brighter water but the sky is totally overexposed. One technique that may already come to mind is using a graduated neutral density filter (or GND). The problem with using a GND in this situation is that although it would cut down on the light and allow me to capture the sky w/o overexposing, the length of the shutter speed would blur the clouds too much for my liking. Take a look at the two closeups below.

The 10 second exposure, decent structure and color
As you can see, the 10 second exposure still has definition in the clouds and even picks up some underlit areas quite nicely. Exactly the kind of detail I want.
 
The 30 second shot below is too long and the cloud movement allows the structure and colors to blur too much. Definitely not what I wanted, but unfortunately this is exactly what you'd get if you used a GND in the field and tried to capture the image in a single shot.  
The 30 second exposure with a simulated GND applied to bring
down the brightness of the sky.

So how do we combine the two?

If you have Lightroom, select the bright and dark image together, then right-click and go to Edit In >> Open as Layers in Photoshop (see image below). If you don't have Lightroom, just open the two images as layers manually.
 

 

 

 

 

 Now that you've got them opened in Photoshop (or in Photoshop Elements), watch the video below to see how quickly and easily you can mask the two images together. You can watch the video in a separate window in HD by clicking here.



After the two were combined I flattened the layers, saved as a TIF, and tweaked the exposure a little more in Lightroom by adding a slightly blue photo filter, boosting saturation a tad, and adding a vignette. After it was all done I ended up with the super flat water and clear clouds I wanted, each element coming from a different shot. It's that easy.

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