OT: Circular and Linear Polarizers . . useful knowledge?

Grazie wrote on 5/20/2004, 11:42 PM
Hi Friends .. . I recently wanted to know the real difference between Linear and Circular Polarizer devices. I wont admit to understanding all of it, but the light-path diags do it for me . . . . relevance for V5? Sometimes you can't do everything in post. Sometimes you gotta do it on site! ( Apologies to John Cline if you think this is too "off-topic" .. .I think it adds to our universal understandings as to what can be done and what is possible with or without filters .. for me understanding what filters "do" takes the guess work out of the creative process .. yeah? )

Okay, okay .. okay .. . This link was posted by another chum. Interesting and informative I think for film makers and understanding how light passes through these devices. Click on the "Learn More" PDF file link .. just over on the right side of the page .. . Vikuiti™ Circular Polarizer Film

Best regards,

Grazie

Comments

farss wrote on 5/21/2004, 3:28 AM
If you need a polarising filter and don't have one on hand a pair of sunglasses can be pressed into service if they're the polarising kind. Excellent for shots of water or to enhance clouds in the sky.
If you're seriously interested in filters one of the dvxuser.com guys has made a DVD showing the effect of most of the Tiffen filters.
Grazie wrote on 5/21/2004, 3:52 AM
. . and I guess polarizer sunglasses without a tint too? Can't remember when I last saw a pair of untinted plain polaroid Sunglasses? Over to you farss ;-)

Grazie
epirb wrote on 5/21/2004, 4:36 AM
speaking of polarizers , I had a freind in that worked for 3m tell me about this. I love to get my hands on like a 12" x 12" piece.
http://www.3m.com/market/omc/om_html/tech_polar_html/applications/vlt.jhtml,
a Little side note:
Right now in some of the Yachts I work on(built over cross the Pond in Plymouth,UK ) we have the "electronic" glass. Basicly Lcd crystals inside, turn it from basicly clear to as opaque as you want it with the turn of a dial.
Guy Bruner wrote on 5/21/2004, 5:35 AM
There is also an excellent explanation of polarizing filters by Cokin.
farss wrote on 5/21/2004, 5:44 AM
They all do seem to have a tint but so long as it's only a ND tint shouldn't affect things too much. Still not as good as a proper filter in a rotation stage. Other problem with the sunglasses is they're not optically flat either so you'll get some minor distortion.

Graduated ND filters can also be very useful in situations where you cannot control lighting. Of course a decent set of glass filters and something to mount them in will costs as much as a camera. Grazie might get 'em a bit cheaper as some of the best ones are made in the UK by Format.
Promist is another filter that is good for making DV look better than it is.
wcoxe1 wrote on 5/21/2004, 5:57 AM
According to Tiffen Co. Linear Polarizers can adversely affect modern light meters. That is the reason for the development of Circular Polarizers.
newbe wrote on 5/21/2004, 6:03 AM
Polarizers, any good for Video?

I wonder, what happens when you make a "pan", the angle to the sun changes, so,what happens then?
richard-courtney wrote on 5/21/2004, 7:55 AM
While Coken may be the cheapy brand I like the simple matte box like holder.

While shooting some cars I was able to rotate the filter to get the best
look off the shiny hood (bonnet for you Grazie!) while I panned.

I can't say I would buy one of each filter because some special effects
filters can be replicated in post production. If you don't get the effect you
want on the first take you may not be able to reverse the effect.

But polarizers I think are a must. Even my wife says the sky colors are so
much better. (I did not tell her it was the $20 filter and not the new camera!)
dvdude wrote on 5/21/2004, 8:06 AM
I pretty much use the rule "if it's outside and sunny, pop the circ pol on and go!". Remember that these filters do also act as ND's too, so the lens is likely to be more open and/or shutter speed will need to be decreased for correct exposure.

The effect a properly aligned circ pol has on a blue sky during a sunny day is totally awesome though, well worth it. Being able to more easily shoot through glass/water is pretty cool too.