Tuesday, December 28, 2004

Polarizer

Hey, did you guys ever wonder what the difference was between a circular and Linear polarizer? I knew the difference, but didn't understand the importance. When I stopped to by a stocking stuffer for jen, a Polarizer for the EOS Rebel, the people at the store were unable to find a linear polarizer. all they had was circular ones, so I shelled over my 27$ and bought it. getting home I did a little research and discovered that the Circular was probably what I really wanted as Its needed so the autofocus will work correctly in modern SLR cameras. I"m not too sure if it is required for Digital Rebel but it can't hurt anything. Read Cokin Filter Systems for more info.

4 comments:

Sarah said...

Nope. I never wondered. But now I don't need to.

forkev said...

i do wonder if i can used a polarized lense to push/focus/align more light through an lcd for a diy projector....

palegreenhorse said...

kev... polarizers do not focus light, they are passive devices, they just absorb what you don't want. the best a polarizer can do is transmit 50% of incomming completely unpolarized light. in reality polarizer let something like 40-48% of the light through if they are good (cheap ones less light). so it isn't a particularly good idea to use a polarizer if you don't have to.

lcd already have polarizers (two) built in and they are crossed. the liquid crystals change the polarization of the light to make it get through or don't change it to make a black screen. so putting another polarizer on your projector project is probably not a good idea (it will just dim the light further). check out how stuff work's explanation, it is bit more complicated in stn lcd's but you get the generagl idea.

k2h said...

re: palegreenhorse
"generagl idea" it reads like you choked on something! I love it.