I noticed today that you can zoom into a photo with on screen buttons. The option appears when you open a pic. The zooming options are hidden behind the "options bar" with the three dots on it. Once you open a pic remove the bar by touching the screen again. Once the bar is removed tap at the lower right corner of the screen exactly where the three dots would have been. You will se "+" and "-" icons there. Although i find this cumbersome, just wanted to inform