Since I bought the Ultra Wide Angle Lens in July, I have even more focused on architecture photography. Around that time, a friend asked me whether I had applied a polarizer to that lens in order to improve my pictures. Although I did not really believe a polarizer would be neccessary, I did some research on the internet and eventually changed my mind. I learned that light resulting from reflections is mostly polarized and can overlay the actual image resulting in pale colors and possible overexposures on affected areas. Also, considering that I predominantly shoot cities and architecture, there is always a substantial amount of glass involved which inevitably reflects light. Light reflected by water is polarized, too. Even tiny water particles in the sky reflect polarized light, desaturating its blue color on the photo.
A polarizer is a filter element that is mounted in front of the main lens of the DSLR camera and reduces or even cancels polarized light under certain conditions. This allows to get a clear view of reflective surfaces and to see through transparent elements that would otherwise be superimposed by reflected light. In addition, the sky will often look darker but more saturated with a polarizer applied. More technical details about polarization can be found in the technical articles later.
Finally, I decided to buy the B+W MRC Nano XS-PRO DIGITAL PREMIUM Polarizer for around 120 USD. The diameter is 67mm to fit my Canon Ultra Wide Angle Lens. Here are some unboxing pictures of the new image enhancer:
I will be updating this post with some live tests as soon as possible!