It looks like iOS 7 adds a digital zoom to the video-camera app. You’ll need to be running it on an iPhone 5, but if you are, you can zoom in 2–3x as you shoot. Plus, it doesn’t appear to be the crappy digital zoom used for stills.
Digital zoom on a stills camera is pretty much the exact same thing as a crop. You just cut away the outer pixels to leave a part of the picture. Go too far and you end up with a fuzzy, pixellated mess.
But because even a 1080p video doesn’t use close to the full amount of pixels on a modern camera sensor, there’s another way to zoom. Instead of just downsampling the entire frame and then blowing that up, you can just chop out a smaller section of the full frame and use that. Here’s an example using real (but probably badly added) numbers:
Say your video image is 1920 x 1080 pixels, and your camera sensor is 8MP and shoots images at 2448 × 3264 pixels (like the photo I just took to check the numbers). As you can see, you could overlay the 1920 x 1080 rectangle on the photo and move it around a fair bit. What I’m saying is that you can effectively zoom to 2x and still be using the bare, untouched pixels.
And this is what the iPhone 5 appears to be doing under iOS 7. I guess the feature needs both the Phone 5’s 8MP sensor and its more powerful processor to do this magic.
Sadly, I have removed iOS 7 from my iPhone because I prefer my phone not to crash and eat its battery in just a few hours, so I can’t test this yet, but you can see a video sent to TUAW from an anonymous developer by following the link below.