Albert, here are the reviews of the TC14E and TC20E from CI. Both were
tested with an AFS2.8/300mm.
1) base test: 300mm alone
4/5 optic. definition at all apertures f/2.8, f/4, f/5.6, f/8
vignetting 0.5 stop at f/2.8, 0.3 stop at f/4, neglictible at f/5.6
0.4% distorsion (pincushion)
2) with the AF-I TC14E
3/5 optic. definition at all apertures T/4, T/5.6, T/8. Nearly 4/5 at
T/8 at the center
vignetting 0.4 stop at T/4, neglictible at T/5.6
neglictible distorsion
neutral color rendition
No loss of the AF original speed of the 300mm
Global note of the TC: 3/5 (including the quality/price ratio)
3) with the AF-I TC20E
3/5 optic. definition at all apertures T/5.6, T/8, T/11. Nearly 4/5
at T/8 at the center
vignetting 0.4 stop at T/5.6, neglictible at T/8
0.3% distorsion (pincushion)
neutral color rendition
Almost no loss of the AF original speed of the 300mm
Global note of the TC: 2/5 (including the quality/price ratio)
Their conclusion is that both TC's are very good performers, but are
extremely expensive (in France, we can get them around 750USD for the TC14E
and 830USD for the TC20E).
Hope this will help you,
Franck
