Originally posted by reivax My main concern is autofocus speed.
I cannot compare the K-30 but I can compare the K5iis against the K3 for you.
Hi Revax,
FWIW personally I would think the K3 with the Tamron would be a good combo for two reasons. Firstly the screw drive seems to be a bit stronger/faster (at least compared to a K5iis) and also the focus tracking of the K3 is vastly superior.
I have the Sigma 70 - 200 and whilst it is a good lens I think the Tamron would be a good match for it on a K3.
There is probably something else you need to consider though. The K3 runs into ISO limitations probably a stop before the K5iis but 3200 can be used on the K3 shooting raw with some post work. (see heavy crop below)
My recommendation? Find a member/shop with a K3, dial in your Tamron , and see what you think. (But keep your K-30 as the second camera for the sports short zoom work)
Cheers Chris