I moved to about twice the distance so the centre circle were only partly resolvable. These are 100% crops, but the pixels of the shot without TC were increased by 1.4x to give the same "resolution" as with the TC. JUsge for yourself. Is it worth losing a stop and spoiling AF by adding the TC? (My lens is sharpest bare at f/11, similar to as found by SLRgear.
Top = bare lens x 1.4n using PhotoShop
Bottom = lens + 1.4xTC
OK. So basically upping the resolution in photoshop will result in almost a same image as using the TC
Just out of curiosity AlanF, how does the center resolve with the 300mm f/2.8 + 2x TC? The 300mm f/2.8 is what I plan to get next.
The 300mm f/2.8 II + 2x TC III is superb. Unless the subject is too close, I always use the x2 in preference to the 1.4. Everyone who has the combination in CR praises it. The version 1 lens is not as good, by all accounts. The focussing is also very snappy on the 5DIII, but not the 7D.
5D IV, 5DS R, 7D II, EOS-M, Powershot G3 X, 400mm DO II, 300/2.8 II, 1.4xTC III, 2xTC III, EF 1.8 STM, EF 70-200/4 IS, EF 24-105, 15-85, 100-400 II, Sigma 10-20, Sigma 150-600mm C, EOS-M 18-55, f/2 22, 11-22