Seriously, WRT 400/f2.8 you're right, nothing wrong. However, for the focal-length starved, the D4/D800 offer superior capability in that they apparently do AF reliably with the TC-20eIII and f/4 lenses - meaning the 500/f4 and 600/f4. Particularly with the 600, that's a significant difference. Vic and I have tried several times to get the TC-20eIII to AF on our D3/D300 bodies with his 600/f4 and it just does not work well enough to even contemplate at a race. But with a D4/800, maybe that's now a reality. I know I could certainly have used the 1200/f8 combo a fair number of times.
> I ... still prefer the TC14E
From an outright IQ perspective, I agree. I have both the TC-14eII and TC-20eIII. But for my purposes - mainly motorsport or birding - the additional focal length greatly outweighs the marginal difference in IQ. Sure the 14 resolves more lpm - there is no question about that. On the other hand, as demonstrated above, the 20eIII is resolving eyelashes at 290 feet - is it really necessary to resolve the driver's retina patterns from only 225 feet? (Can I even get within 225 feet, even if I want to steal his retina patterns? )
> My TC20E isn't recommended.Its an earlier version.
More precisely you don't have the aspherical formulation. I agree: the earlier TC-20eI or 20eII are NOT recommended. The III is a LOT better, and especially so on the 400/f2.8. (Bear in mind that I have the 400/f2.8 AFS-II. The 400/f2.8 AFS VR-II is said to be both better in the first place and also better matched to the TC-20eIII.)
> Nikon isn't getting it right first time... I get tired of spending money on a product that isn't ready.
In their defense, 2x TCs have never been a great idea until the TC-20eIII, at least nothing that could be used in F mount. I guess the viability of manufacturing a TC with an aspheric element made all the difference - in an earlier age the 28/f1.4 AFD cost almost 10x the 28/f2.8, mostly due to a couple of hand-ground, super-expensive aspheric elements. I doubt many folks would have laid down $1000 in 1980 dollars for a hypothetical TC-301aspheric, even if it mated with the 400/f3.5 AIS very well.
> trade my TC17E and TC20E in?
I'd guess that if you sold them, you'd get enough between the two to mostly finance a TC-20eIII. Would you really use all three? I sure don't. I barely use the TC-14 - I don't even put it in the bag most of the time. (I usually use it with the 70-200.) I am pretty certain that I'd almost never use a TC-17e even if I had it.
_____ Brian... a bicoastal Nikonian and Team Member
My gallery is online. Comments and critique welcomed any time!