Hi, I need to buy an all around lense for the least amount of money. I was thinking about Tamron 18-200mm F/3.5-6.3 Di III VC for the Nex but then I thought, why not buy the Tamron AF 18-200mm F/3.5-6.3 XR Di II LD for 1/4 of the price and then some sort of adapter? Is this possible? Would it compromise some quality or functions? What adapter do I need? Sorry for so many questions but I'm a newbie. Thanks in advance!