Sådana är vi mäniskor, känner igen det från bilsidan. Jag tackar för tipsen, har också FF med för och nackdelar. Beträffande TC 2,0 så läste jag följande som kanske till viss del förklarar att det fungerar bra på FF:
Sharpness
The Canon 300mm ƒ/2.8 is one of the sharpest lenses we've ever tested. This is a lens designed to be used wide open at ƒ/2.8, and it shows in the test results. On a subframe 20D at ƒ/2.8, the far right edge of the frame barely reaches 1.5 blur units, and the rest of the frame edges just above 1 blur unit. This performance improves (as if it had much room to improve) by ƒ/4, where it is essentially tack-sharp across the frame. It's just as sharp through ƒ/5.6-8, and by ƒ/11 we begin to see the effects of diffraction limiting, though at this level to say that the sharpness is degrading needs some qualification. Sharpness hits 1.5 blur units at ƒ/11, and 2 units by ƒ/16. It's possible to shoot at ƒ/32, but here you actually encounter some legitimate softness issues at 5 blur units across the frame. This really isn't a lens you're going to be shooting at ƒ/32, though.
Performance on a full-frame 5D is equally impressive. The lens is really challenged by the full-frame sensor, with 1.5 blur units in the central region and just shy of 2 blur units in the corners at ƒ/2.8. This kind of performance is the norm through to ƒ/11, not getting any better or worse; at ƒ/11 things even out somewhat and you get a consistent 1.5 blur units across the frame. It never hits the ''tack-sharp'' results we saw on the sub-frame 20D, but the results are still excellent. By ƒ/16 diffraction limiting sets in, with sharpness showing up at 2 blur units across the frame, and the lens produces fairly soft images at ƒ/22-32 (2.5 and 4 blur units respectively).
Jag hoppsa nu att jag lyckas få tag på ett beg 300/2,8 sedan blir mitt 500/4,5 från Sigma till salu.
Happy shooting och tack för bra svar!
