After spending a fortune on L glass including the 24-105 IS and the 70-200 2.8 IS, i was looking for a cheaper alternative wide angle than the 17-40L or the 17-55 IS,
I have previously owned the 17-40L and liked it but found it a little short, and the f4 although not bad 2.8 would be better,
After reading the reviews of the Tamron 17-50 2.8 here i took the plunge and boy was i ever pleased i did,
Build quality is excellent, smooth operation in use, and totally
incredible image quality, sharpness is just astounding!
I can honestly say that this lens produces better images out of camera than the 17-40L i owned.........at less than half the price!
Yes the focus whines a little but it's no problem and it's quick anyway,
If you are thinking of getting one of these........GET ONE Now!