I have a Nikon D50. Just bought a Tamron 17-50mm lens used. And I am a novice. Shoot in aperture mode mostly, and sometimes auto mode. This picture just is not sharp. It should be with this lens. Does the camera need a cleaning, or is it me. Getting so frustrated. Thought this lens might pick up my enthusiasm again. Here is a smaller shot that the previous owner took with the same lens and also a D50.