The circular polarizer filter is, by far, my favorite filter type.
These filters are most commonly threaded onto the end of a lens.
Because Canon’s big white lenses have a huge front objective lens size, these threaded filters are not practical.
Therefore, Canon provides a different type of circular polarizer filter option, the Canon 52mm Drop-In Circular Polarizer Filter.
Neutral density filters reduce the amount of light reaching the camera’s imaging sensor.
The light reduction is even across the visible spectrum (or it should be).
With less light reaching the imaging sensor, a longer exposure or a wider aperture can be used.
The wider aperture can be used to avoid the effects of diffraction or to achieve a shallow depth of field under even full sunlight.
If someone took my circular polarizer filters away, I don’t know what I would do.
I would be completely lost when photographing landscapes.
And in many other indoor and outdoor situations, I would feel very limited.
No other filter will do more to add “pop” to your images.
Getting better image quality by using a circular polarizer filter is so easy that it almost feels like cheating.
On a DSLR camera, the primary purpose of a Clear, UV or Skylight filter is to protect the front lens element.
You will seldom see a difference in your image quality caused by using a high quality protective filter, but whether or not to use a protection filter is the big running debate.
Neither side is wrong in this debate, but they have differing opinions – and the freedom of choice.