Nikon D300 - Wikipedia The Nikon D300 is a 12.3-megapixel semi-professional DX format digital single-lens reflex camera that Nikon Corporation announced on 23 August 2007 along with the Nikon D3 FX format camera. The D300 was discontinued by Nikon on September 11, 2009, being replaced by the modified Nikon D300S, which was released July 30, 2009 D300S remained the Nikon 70-200mm f/2.8 FL Review - Ken Rockwell Nikon 70-200mm f/2.8 FL on Nikon D5. bigger. Nikon 70-200 2.8 FL. bigger. A/m M/a M switch. This is the AF/MF switch. It has two AF positions, A/m and M/a. A/m tends to ignore accidental knocks of the manual focus ring, while M/a responds to even the smallest turn of the focus ring. M is Manual focus only. AF doesn't work. FULL ∞-5m switch