I heard UV Filter is recommended on lens for SLR cameras to protect it from UV rays. Do you use them on your lens? How do you select which filter is good for each lens (ie. not to degrade the image quality)? I have Tamron AF28-75mm F/2.8, Canon 70-200mm f/2.8L usm, 50mm f/1.4, 100mm f/2.8.