Filter Factor Polarizers

[hortense]

Estimates how many stops of increased exposure are required using a circular polarizer? I have no in-camera exposure meter.

 

[Dave Parker]

Depending on the brand, I have seen anywhere from 1.75 to 3 stops, there should be a filter factor printed on the rim of the filter, what brand is it?

Dave

 

[jeroldharter]

I think that a filter factor of 2.5 (=1 1/3 stops) is typical.

 

[Christopher Walrath]

Jared is close to on. but a circular polarizer increases/decreases in effect when rotated. This can swing a half a stop one way or the other. just something to bear in mind. Try using a hand held meter and meter the filter that way. Might get you closer than guessing.

 

[hortense]

Depending on the brand, I have seen anywhere from 1.75 to 3 stops, there should be a filter factor printed on the rim of the filter, what brand is it?
Dave

Thanks Dave . The rim IS marked in 1-stop increment (plus/minus up to 2-stops). Didn’t’ look at it! Thanks for your help!
MAC

 

[Ole]

There is no difference in the filter facton between circular and linear polarisers.

Checking the meter reading while rotating shows how much polarised light is being absorbed by the filter, so IMO it makes more sense to use a fixed factor. After all, you want the brigh reflections to be darker, don't you?

A second way to use polarisers is just the opposite: to enhance reflections. When rotated so that the reflections are strongest that light goes straight through, the rest of the scene is still 2 1/3 stops darker.

 

[hortense]

... Try using a hand held meter and meter the filter that way. Might get you closer than guessing.

Flash - Sounds like you've done this. I'll give it a try.
Thanks,
MAC

 

[hortense]

There is no difference in the filter facton between circular and linear polarisers.

Checking the meter reading while rotating shows how much polarised light is being absorbed by the filter, so IMO it makes more sense to use a fixed factor. After all, you want the brigh reflections to be darker, don't you?

A second way to use polarisers is just the opposite: to enhance reflections. When rotated so that the reflections are strongest that light goes straight through, the rest of the scene is still 2 1/3 stops darker.

Ole - This sounds good. Thanks, MAC.

.. and ALL you guys ... truly a knowledge tank.

 

[Soeren]

Stupid question alert.
I know the Polariser takes out reflections and darken the sky to a degree depending on angle to the sun etc. I also know that an incamera meter will give different exposures because of that but I though the filterfactor should be constant since those effects are desired and if using a handheld meter for incident metering it should result in the correct exposure of the ground.
Am I totally wrong ?
Cheers, Søren

 

[Ole]

Søren, you're totally right. See my answer above.

 

[Soeren]

Søren, you're totally right. See my answer above.

Yeah you beat me to it. I'll better take a cource in fast writing
Cheers, Søren

 

[Jim Jones]

Stupid question alert.
. . . if using a handheld meter for incident metering it should result in the correct exposure of the ground.
Am I totally wrong ?
Cheers, Søren

You would be right if you were using reflected light metering.

 

[titrisol]

PS Question... does any compnay still make warm polarizers?

 

[Dave Parker]

PS Question... does any compnay still make warm polarizers?

Moose and Singh Ray as well as Hoya, Tiffen, there are still quite a few that make Warm Polarizers, they are quite popular in the nature photography and landscape arenas.

Dave

 

[titrisol]

thanks, mine got lost during the last move....

 

[Nick Zentena]

All the Moose filter info from the Moose website seems to have been removed. You can still get it from google's cache. In addition the Hoya Warm [aka Moose] that came in the mail today has no mention of Moose. My guess is the contract is up between the two.

http://72.14.203.104/search?q=cache...g+Circular+Polarizer&hl=en&gl=ca&ct=clnk&cd=1