Toronto Photography Meetup Group

Can anyone fill me in on this: I know Tim was mentioning to me that you can use two polarizers to cut down *heavily* on the level of light getting through the lens.

He was saying you can stack a CP with a linear polarizer (but order is apparently important)... can anyone confirm with a link cause I'm on the site formerly known as HVstar looking at placing an order for some other stuff.

If you're trying to cut down the amount of light in order to get a longer exposure or be able to shoot with a large aperture in bright light, you might be better off getting a neutral density filter. You can get them in different densities depending on how much light you need to cut. This way you can use a single filter instead of stacking more glass in front of your lens and preserve image sharpness.

I already have ND filters, but I want to use this to go completely overboard on cutting down the light, into ND double digit or triple digit territory.

How about this discussion?

http://www.pentaxforums.com/forums/gene ... rizer.html

The effect is kinda weird as I'm playing with my one CPL and a pair of sunglasses -- the thing is that the CPL seems to be directional. With the CPL in front, I can make color shifts. With the sunglasses in front, things will darken. The reverse happens if I turn the CPL around. So, ultimately order may not matter since you can always change the order.

I'm interested in placing an order with hvstar/maxsaver too. Would you mind if I join you?

If you want to really kill the light then there's the ND x400 which is a 9-stop ND filter.

This is something I've done...first you screw on the circular polarizer, and then the linear polarizer. If you do it the other way around the effect will be cancelled out by the 1/4 wave plate inside the circular polarizer. I've also done it with two linear polarizers.

Your exposure meter and/or focus sensor may be affected as well depending on your camera design...you may have to focus without this one the camera first and lock the focus/switch to MF.

One note though, if you do this you should probably order two or more filter wrenches if you intend to separate the two polarizers, not to mention make it easy to remove from the camera if they get stuck.

Better to use 2 cheap linear polarizers and compensate for misreading by the light meter.


Otherwise the circular polarizer (CP) has to be the closest to the sensor. A circular polarizer is made up of a linear polarizer (LP) and a quarter wave plate (QWP) so order is important. If you have an LCD screen hold CP up to the screen and rotate and the screen will go black if the QWP is closest to your eye or camera, not much will happen if you reverse the filter.

Get an ND400x. I have one.. I'm able to do exposures approximately 100 seconds long in the bright, bright sunlight. Stack a second one on top if you're looking for a longer exposure. I'd also recommend using graduated ND filters and a CPL with it.

Two polarizers may affect your AF. On my 1Ds with the 85 1.8 and a CP in front of a linear, the AF was hunting excessively on glass surfaces. With the 17-40L there were colour shifts at 17mm where there should have been glare.

I have heard elsewhere that stacking is a hit and miss given different lenses.