Thanks for the info, we usually use UV or Skylight filter to reduces the excessive bluishness / absorbs the UV rays and protect the lens.
Some photographers also use light balancing filter (81C)
under Singapore climate. What is your opinion ?
UV rays absorption are mostly more prominent in high altitude. Singapore is low altitude, and high humidity, and surrounded by the sea, so a UV filter here only serves to protect the lens, without much effect on the photos. Of course, people who don't use filters may feel otherwise, cause you are putting a layer of glass infront of the lens. I personally don't see image degradation due to use of filters.
I have a skylight filter on my 70-300mm lens, but it's mainly use as protection for the lens.
I don't use light balancing filter, although I do have Cir-pol filters for my lenses. I believe that most of my photos can be adjusted through image editing software. In the past, when i use film, I do use other filters to enhance my landscape/sunrise/sunset shots. However, I am only a traveller with limited experience, so cannot comment much.