Tapping on the Menu button reveals different features and settings for snapping a photo. Notice how the viewfinder blacked out when I opened the menu on this occasion? This is one of many odd bugs I experienced when testing the app.
Enable Lightroom in the app's settings by tapping on More, followed by Lightroom. This forces the app to save your photos within the app, preventing your camera roll from being overrun by photos (especially if you use the rapid-fire feature of ProCamera 7).
The guide included in the Settings section of ProCamera 7 is the most thorough guide I've seen within an app. It's well-done and can be a huge help to those less familiar with common icons and settings. Use it.
While this looks like a pretty sweet shot and filter effect, it's not. This occurred after tapping on the shutter button with rapid fire enabled. A reboot of my iPhone 5S was required to get the app to work properly again.