People always ask me what that gray thing is during a photoshoot. It's how I set the correct settings for using the flash. Then they wonder why I use flash outside during the daylight. Here's why...
What does "blown skies" mean? It is where the sky looks white in photos. It's very common for natural light photographers. With them, it's either show the colors in the sky OR show the subject. If they set the camera to show the sky, the subject will be blacked out like a silhouette. If they set the camera to show the subject, the sky turns white. This is one of the big benefits to using off camera flash during the day outdoors. You can capture a beautiful sky with all the gorgeous colors at the same time you can have light to see your subject.
In this first image, you can see that while my subject is showing up beautifully, I'm missing the gorgeous sunset over the river. I had the subject set up and we taking photos along the river side. I turned towards the sunset over the river. I take a shot and I can see that the skies are blown. Look at all that white. I can barely see the bridge.
Gray card to the rescue. I turn off my flash. Take a shot using only the ambient light. Look at how beautiful the sky actually is.
Then, using the gray card positioned at my subject and facing the camera, I set the exposure of just the subject and the flash. So I don't adjust my camera settings. I know the sky looks great. The only thing I touch is the trigger to adjust the flash settings to have my histogram right down the middle so I know my exposure is perfect.
