I've just managed to dig out some of my family's old filters. These are the:
1. B+W KB3 1.2x
Look up on the net, and it says these are for dawn/dusk kind of scenarios. What does KB3 and 1.2x stands for? Some exposure compensation? Also, can it be used for modern dSLRs?
2. Hoya PL filter
This filter is dated somewhere in the late 70s, and just stated as PL. So can the user tell it is a linear or circular? And also, is it appropriate for today's cameras?
Haven't tried out yet cos I'm still busy cleaning it! Thanks in advance!