I have had this lens for about 2 years and I have had the filter on it the whole time. It is in great condition and takes wonderful pictures. It is super sharp, even wide open at f2.

The EF 135mm f/2L USM Lens from Canon is designed to meet the needs of a wide range of advanced amateurs and professionals. With its f/2 maximum aperture, it is effective in low light situations and able to obtain shallow depth of field with superior background blur. A ten element optical formula with two UD-glass elements serves to correct residual aberrations, resulting in superb sharpness and high image quality.
An ultrasonic autofocus motor (USM) enables fast, smooth and silent autofocus and fulltime manual override allows for precise manual focus even in autofocus mode. The minimum focus distance for the 135mm f/2 is 3.0'. A switch on the lens barrel enables you to adjust the focusing distance range for faster autofocus speed. It is a stellar portrait and available light lens and is fully compatible with the Canon EF1.4x II and EF2.0x II extenders.