Most likely this is 84B "Still Photographic Specialist". The U.S. Army does not seem to have had an MOS called "Combat Photographer" during the Vietnam era, or any other combination. Roger Hillerby's short recollection/memoir of Vietnam tells of how he started as a Still Cameraman who eventually became a combat photographer. ^1

Most searches agree that "Still Photographer" was the US Army MOS for Combat Cameraman. As an aside, the USMC actually does have the MOS: it is 4671 "Combat Photographer". This is that source, grain of salt, as it is not official so proceed with caution.

The current {2015} MOS appears to be 25V

Sources

^1 Hunter Killer Squadron, Page 38, via books.google

^2 USMC yearbook project

^3 Goarmy.com search

^4 Vietnam era MOS codes #1

^5 Vietnam era MOS codes #2

^6 Vietnam era MOS codes #3

EDIT

Read my reply below, I found data of an additional MOS in use by the US Army