[stoppingdown]

... in the meantime, I've pre-ordered the Sigma MC-11 adapter at Amazon.de... let's see how long it will take. I'll try to resolve the Sport vs Contemporary dilemma in the next days. I've added a further consideration. Obviously I like to spend less, but money in this case aren't the primary criterion. My point is that I'd like to be sure that, if I pay for something more, I'll use it. I hate to spend money for features I don't need or I'm unable to use. It seems there's some extra sharpness at 600mm for the S, and that's a point. The third, negative, criterion is weight: the S version is almost 3kg, compared to the 2kg of the C version. It's unlikely that I carry this kind of lens for longer than short hikes, so in the end 2kg vs 3kg might be not important. OTOH, the old Nikon D7000 + AFS 300 f/4 combo weights exactly the same as the A6300 plus the C version... This means that, even though my back is worse than years ago, if I was able to carry the old combo, I'd be able to carry the new combo - just less frequently. Adding one kg would be a worse scenario. So the C version might be slightly more versatile...