Time Zone old IOS 6.1.3 pic to Mac OX 10.6.8

Why do old iphone photos uploaded to Iphoto show my current time zone of my Macbook, but manual upload/right click/Get Info shows true time zone of photo? GPS was off. IOS 6.1.3 was on an Iphone 4S and photo was taken in May 2013. Mac OX 10.6.8 Iphoto 11 9.2.3. Need a way to prove time zone pic was taken. Other software programs, online and otherwise do not show time zone. Why does Get Info. show time zone while other software/online services do not? Is there software/online service out there to show true time zone photo was taken? Thanks!