Advantages: Initial Cost is far less then the original Canon and Nikon lenses Disadvantages: The only negative point I see is the requirement of UV protection film on the lens for protection.
I have been using Tamron lens and have particularly a very good experience, the prices too are very commutative and obviously the picture quality is on par with the original , the price difference between the genuine Canon and Nikkon lenses to Tamron len ...
Advantages: Good build quality, inexpensive and offers a huge zoom range without lens changes. Disadvantages: A slight lack of sharpness and colour reproduction when compared to more expensive lenses.
There are many people interested in photography and many of them eventually choose to become DSLR camera owners and users, and once they have forked out huge amounts of money for their chosen DSLR camera they then find that their spending is far from over ...