in searching this combination, nikon site states the lens won't autofocus whilst forum posts here and elsewhere state you can autofocus..albeit with the usual and customary low light and aperture limitations.
An f/4 lens with TC 2.0 becomes an f/8 lens. New bodies like the D4 and D800 have an improved autofocus sensor that provides AF operation down to f/8, when using the center AF sensor. So under these conditions, AF is officially supported by Nikon. Older bodies like the D700 only officially allow AF down to f/5.6.
That said, AF does work somewhat even on those older bodies, when using it in good light, but it is very, very slow. So you cannot complain to Nikon if it does not work for a given scene, but they don't disable it completely. I found it rather un-useable, though. So if you plan to use AF with that lens and TC 2, better use a new body that offficially supports it.
On some of the newer bodies, one or more of the AF sensors is sensitive enough to function with apertures as low as f8. As far as I know these include the D3, D3s, D4, D800, D600 and D7100
AF performance will be reduced to the area covered by the f8 capable sensors and on some cameras it may only be the centre sensor.
In bright light, AF may work even if the body does not have f8 capable sensors but the speed and accuracy may be reduced.
e.g. on D800 the centre 15 of 51 sensors are f8 capable. Therefore I would not expect to get full 3D matrix tracking AF across the frame with an f8 lens combo but it should be able to AF on a relatively slow moving subject in the central part of the frame.
Tom is exactly right. Nikon does not update specs and lens manuals for new bodies.
The f/8 AF of new cameras is not with all sensors. The center sensor performs at f/8 - and possibly some of the other cross sensors with new cameras. Other sensors may only perform at f/5.6 or f/4 even on new cameras.
AF occurs with the aperture wide open - regardless of what aperture you are using. Wide open with the 300 f/4 and 2.0 teleconverter is f/8. You'll still need to stop down a stop or two for optimal sharpness. And don't expect optimal sharpness to match the bare lens - you will get some image deterioration and it may or may not be acceptable.
Canon actually uses software in the camera to prevent the camera from focusing beyond the level indicated. There are work arounds.
I have fund that the TC-17E works quite reliable on the 300 f/4 af-s and a d300 or d700 while the TC-20Eiii requires very good light and contrast to AF reliable on this lens and body combination. My TC-17E is allmost glued to my 300 f/4.
I have no experience with the newer bodies.
I suggest you consider the possibility of a TC-17E.
>I suggest you consider the possibility of a TC-17E.
I second this. I have all 3 TCs, and regardless of AF, on my 300/4 AFS lens, I found the image quality with TC 1.4 to be excellent, almost indistinguishable from the bare lens, with TC 1.7 to be acceptable with some degradation visible, and with the TC 2.0 (I have the new model III) to be not good enough for my taste. I found the TC 2.0 works best with f/2 and f/2.8 lenses.
i have a D200 so with the 1/7 I would be concerned as I think the D300 has better autofocus????.i just got the TC14e which works great. so not sure if I want to get an extra 90mm of length for another $250-300...i could probably put that money to better use somewhere else.