Light reading with a polarizer.

[brokenflashlight]

I've been playing around with my linear polarizer and other filters today with a roll of Tri-X. When I have the polarizer turned to it's "darkest" position my light meter seems to register more light, closing the aperture up by about one stop. When it's in its "brightest" position it reads less light, opening it by a stop. Why, if it looks much darker through the viewfinder, would there be more light entering than when it looks brighter? Seems counterintuitive.

[IShootR8]

I don't know the reason why, but I've read that linear polarizing filters cannot be metered (and autofocused) thru properly.

[brokenflashlight]

I don't know the reason why, but I've read that linear polarizing filters cannot be metered (and autofocused) thru properly.

Oh really. That sucks. I hope I didn`t waste my film.

[cdodkin]

Most polarizers wil have an exposure adjustment factor between 1.5 and 2 stops - depending on brand/type.

So either adjust accordingly on manual exposure, or use an external light meter with exposure compensation, to guarantee correct exposure every time.

I use a Sekonic L-358



This has a cine mode, where you set ISO, and FPS, and it gives you f-stop with the ability to dial in exposure comp for filters etc.

[brokenflashlight]

But shouldn`t the through-the-lens meter automatically adjust properly to external filters? Why are polarizers different in that regard?

Also, I`m shooting with a Canon 814XL-S. It does have exposure compensation.

[IShootR8]

But shouldn`t the through-the-lens meter automatically adjust properly to external filters? Why are polarizers different in that regard?

Also, I`m shooting with a Canon 814XL-S. It does have exposure compensation.

There's a bit of an explanation here:

[IShootR8]

Sorry about that, put in img tags instead of url tags...

http://camerapedia.wikia.com/wiki/Polarizer

[BAC]

Sorry about that, put in img tags instead of url tags...

http://camerapedia.wikia.com/wiki/Polarizer

I used a polarizing filter a few times last year while filming water. I was using a Bolex 155 and had the linear polarizing filter oriented horizontally. It came out a little under exposed but still ok for my use. I assumed that the internal meter would compensate for it but after reading that article it makes sense why it underexposed.

[S8 Booster]

you can use a CIR polarizer, then there is no fuzz with the exposure.

shoot......