The problem with viewing photos on an iPhone, or any phone for that matter, is the size. You'll never see the detail you would when viewing a printed photo or even the same image on a tablet or computer. Fortunately, the iPhone offers two methods to zoom in on your photos, enabling you to better see the fine details.
Open an image you'd like to zoom see in more detail. Touch the screen with two fingers and move them away from each other to zoom in. To zoom out again, make a pinching motion -- the opposite of the zooming in motion.
While viewing an image, tap it twice quickly to zoom in. This method offers less fine control than the pinching method, but provides a quick way to zoom in. To zoom out again, double-tap the image one more time.
These zooming methods work in many other apps, too. For instance, you can use these methods to zoom in on a Web page and make the text or photos larger.