One of the problems pinhole photographers (like me) have is getting exposures. When you use a camera that has f/108 as its fixed setting, it gets a bit difficult when you have to calculate exposures. Using your iPhone, with ExifWizard, you can now check out exposures quickly. Take a picture with your iPhone, open up ExifWizard and you'll see the exposure. Once you have the exposure, you can calibrate the exposure for your pinhole camera. It takes some math, but the iPhone makes it much easier.