Bob,
several years ago, when I first got in Digital SLR photography, I joined up with a really nice forum. Everybody was in a big discussion about how best to impact your photography with all the different DSLR bodies that were being introduced, from introductory, pro-consumer thru professional level bodies ... but the one constant in the entire equation was GLASS.
It was generally accepted and take confidence in knowing that having
decent glass to shoot through is the BEST and most profound thing you can do in your photography to improve it. New lenses that are under the two hundred dollar ($200) mark are extremely
dubious and probably should be ignored The TAMRONs are closely related to Minolta/SONY through business over the past two decades and probably will provide you with substantive and decidedly reliable operation. Their zooms are proving to be very capable and a cost-effective alternative to purchasing the rather higher priced SONY optics.
So, buy with confidence, Bob. This is nothing new, but should be a substantial improvement in focusing and use of light.
Best of luck and drop in on and maybe join the
DCRP SONY DSLR Fourm (<- click here)