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cr500
02-11-2016, 9:28pm
I am looking for a 52mm linear polarised filter which does not block off too much light. I see Hoya advertise that their new circular polarised filter needs less stop than other filters but they do not show a linear filter. Does anyone know where would be a good place to look for a good quality linear filter?

tandeejay
02-11-2016, 9:59pm
by it's very nature, a polarizer is going to block a certain amount of light, I think it is about 1.5 - 2 stops.

Check out this article on circular and linear polarizers. https://en.wikipedia.org/wiki/Polarizing_filter_(photography)

Any reason your after a linear polariser? From the above article:


There are two types of polarizing filters readily available, linear and "circular", which have exactly the same effect photographically. But the metering and auto-focus sensors in certain cameras, including virtually all auto-focus SLRs, will not work properly with linear polarizers because the beam splitters used to split off the light for focusing and metering are polarization-dependent. Linearly-polarized light may also defeat the action of the Anti-aliasing filter (Low-pass filter) on the imaging sensor

cr500
03-11-2016, 10:43am
by it's very nature, a polarizer is going to block a certain amount of light, I think it is about 1.5 - 2 stops.

:
That is what I had thought as well, so is the [Coy name removed] advertising maybe not quite so accurate about needing only 1/2 to one stop due to its better light transmission? I was hoping some newer miracle coatings may have reduced the amount of light lost through polarisation filtering?

Cage
03-11-2016, 1:13pm
Just happened to be looking at this as I'm about to sell a B&W CPL filter.

From their website:


B+W Polarizers increase color saturation and reduce reflections. The neutral gray color and plane parallel polarizer material guarantee optimal image results. High-quality optical glass ensures excellent pictorial quality. The filter factor varies according to how the filter is positioned in relation to the sun. Filter factor is between 2.3 and 2.8.

Linear and circular polarizers both consist of a linear polarizer foil but differ in their construction in the following way. Modern SLR cameras have have a beam-splitting prism that sends part of the incoming light to the meter and part to the viewfinder. The effect is that the light entering the meter is partially polarized by the beam-splitter. A linear polarized placed on the lens of such a system will act as a second polarizer and block light to the meter by a degree dependent on the angle between the prism and the polarizer on the lens. The result is incorrect exposure/aperture values from the meter. The circular polarizer circumvents this problem through the addition of a 1/4-wave retarder, or delay, foil. This ensures that the linearly polarized light is changed into a rotation that appears unpolarized to the meter, resulting in proper exposure/aperture readings.

cr500
03-11-2016, 2:10pm
Oops, my bad, I should have carried that the linear polarizer would not be for my digital camera.