Best Polarizer for removing reflections
Posted 07 February 2009 - 02:58 PM
Are some polarizers better than others, or does it only depend on the angle you shoot from?
If they do differ what are you favourite makes/brands?
Also, what is the best angle to eliminate reflections from cars (I read 30 degrees between camera and surface, 30 degrees between surface and reflection)
Posted 07 February 2009 - 03:59 PM
More specialist types involve the use of colour filter dyes for the palings, as opposed to an opaque black - these filters variably tint areas of the image in response to the degree of polarisation, although that's probably not what you want here and this is a special case. They were used on Planet of the Apes to selectively tint the sky of the supposedly alien world.
The major technical variability of polarising filters is the application of a quarter-wave retarding layer on the back surface, which has the effect of depolarising (or more correctly, circularly polarising) the light once it's been processed in the filter. These are referred to as "circular polarisers". This is done purely so as not to confuse the automatic focus systems in many DSLRs, which often use pellicle or semi-silvered beam splitters so that the sensors can see what the camera is looking at, which are sensitive to polarisation. The only difference this makes is that the thing doesn't work when it's the wrong way round, and you could possibly argue that the additional layer costs you some optical quality.
So in general, a pola is a pola. As to angles, go and look up Brewster Angle on Wikipedia.
Posted 21 February 2009 - 05:13 PM
On the topic of Pola's. Is their physically a difference between a "True Pola" and a standard Pola? or is it just a marketing thing used by schenider.