Late last year, I switched from a Nikon 400mm f/2.8 VR II to a Nikon 600mm f/4 VR II as my primary long lens. It was an agonizing decision, and I knew both options had their advantages and limitations. I thought I'd write this post to give some insight into my reasons behind the switch, as there may be others out there trying to make this same decision that may benefit from it.

The case for the 400mm

• Amazing sharpness even wide open
• Greak bokeh and ability to isolate the subject with shallow depth of field
• Works well paired with the TC-20EIII teleconverter for an 800mm f/5.6 lens
• A little lighter and shorter

• The case for the 600mm

• Holds its own in the sharpness department

• Autofocuses with the TC-17 and TC-20 teleconverters on both the D800 and D4. 

I used the 400mm for over 3 years, mostly at 800mm with the TC-20 teleconverter (version III - all the other versions are junk!). This amazing lens produced stellar image after stellar image, and if you asked me a year ago I would never have dreamed of parting with it. However, when the D800 and D4 bodies came out sporting autofocus at f/8 I started reconsidering my position. I ultimately went with the 600 because not being able to shoot at 400mm wasn't a big deal, but being able to shoot at 1200mm was (to me) a game changer.