Even if you're not into HDR photography, this is one to check out. High Dynamic Range photography creates an image from multiple exposures that are combined to overcome the limitations of automatic exposure control in cameras. The technique can recover details that would be lost in shadows, and keep bright areas, like the sky from blowing out.
The update to Pro HDR, which has just been released, has a new fully automatic mode. Instead of taking two pictures with your iPhone, and manually pointing to the brightest and darkest areas, this new option analyzes the scene, sets the exposure accordingly, and then takes the two images without any user intervention. You can also use the manual mode if you prefer. The app also claims faster image capture and better alignment.
I gave the app a dry run last night and today under our bright Arizona skies. The app worked well, as expected. The auto mode made getting an HDR photo very easy, you just want to be sure to hold the camera steady as the two pictures are taken. You don't need a tripod to take the pictures, and they aligned well, and the combining was smooth and created a much better picture than I would have gotten just using the iPhone metering.
I've used an earlier version of Pro HDR on a photo trip to Northern Arizona recently, and it did surprisingly well. This new version should do even better. Remember, HDR photography is great for landscapes or indoor pictures, especially when a bright window would otherwise mess up a scene. HDR is not so good for portraits, unless you subjects can hold very still.
Pro HDR is US $1.99 at the app store. It works on a 3GS or iPhone 4 and requires iOS 4.0 or later. If you have this app already, grab the free update. If you don't, I think it is a worthwhile investment for every iPhone camera user.If you check the gallery you can see how the two original images were combined into one very pleasing photo. Note: These aren't meant to be pictures you'd hang in a gallery, just quick examples of how the exposures are combined.