Nikon escalated competition in one of the hotter fields of photography, entry-level DSLRs, with a midnight introduction Thursday for the D3200. The sequel to the D3100 ups the resolution dramatically, from 14 to 24 megapixels, while adding a unique Wi-Fi component. Adding a WU-1a wireless adapter will let users share photos directly to a nearby smartphone, letting photographers post online and even preview or control the camera remotely.
