Originally posted by lytefunk
heheh nah.. its ok =)
was just rather surprised at what a circular polariser can do..
So in most cases, do you actually use the polariser?
Can it replace the UV filter as the permanent filter on the lens? Since most of the time, its actually good to remove reflections (most lah.. not all of course)
Any logic of still using the UV filter then?
Another question is, do you stack UV and circular polariser?
Well I thought a technical explanation would be a better answer than a short "yes".
The polarizer works by blocking part of the light that is not in line with the polarizing axis (pardon the technical stuff again). So you will always get some level of light loss (1 to 2 stops), which may not work to your advantage at low light situations.
Also, a polarizer may not be effective at blocking UV, unless it has special coatings to do that. There are UV+polarizer combo filters. The advantage is to remove the need to stack a UV filter and a polarizer, which then minimizes the chances of vignetting when shooting at wide angles. Of couse, this type of polarizer will cost more.
For digital cameras, the CCD may already have UV and IR filtering built in. Furthermore, modern lens coating may already be UV blocking (like eyeglass coatings). As such, there is no real need for a UV filter except to protect the lens from being scratched.
So when using a polarizer, I do not see a need to stack a UV filter. It increases the chances of flaring and double image (reflection between the filter glass layers) and the chances of vignetting (if you shoot at wide angles).
On my CP995, I have used a UV filter on and off and did not really notice any negative effects on the image quality when I am not using it.
- Roy