[jaieger]

Hey all,

I've recently read up a bunch on filters, and decided that I'd really like to use an ND filter for some long exposure daylight shots, which is something I like playing around with. However, in the interest of being cheap/knocking out two birds with one stone, is it advisable/okay/doable to use a polarizer also as an ND filter?

[Nachodog]

Yes. A CPL will reduce your available light by 1 or 2 stops. I've heard of people stacking an ND + CPL to get even slower shutter speeds.

[jcob]

A polarizer will definitely reduce the light going through the lens a little bit, but it's not really enough to do long exposures during daylight by itself (depending on how long of an exposure you want to do). I've used 2 stop and 3 stop ND filters with a CPL before and still have only been able to get about a 3-second exposure in daylight. I've also read, though, that you can stack two polarizers to make a "variable" ND filter and rotate the polarizers to change how strong it is. That's definitely something that you should look into, since it will probably be cheaper than getting a bunch of ND filters. But again, it depends on the conditions that you are shooting in and how long of an exposure that you want.

[jaieger]

A polarizer will definitely reduce the light going through the lens a little bit, but it's not really enough to do long exposures during daylight by itself (depending on how long of an exposure you want to do). I've used 2 stop and 3 stop ND filters with a CPL before and still have only been able to get about a 3-second exposure in daylight. I've also read, though, that you can stack two polarizers to make a "variable" ND filter and rotate the polarizers to change how strong it is. That's definitely something that you should look into, since it will probably be cheaper than getting a bunch of ND filters. But again, it depends on the conditions that you are shooting in and how long of an exposure that you want.

To be honest, 3 seconds is about what I'm looking for, so that sounds pretty decent to me. Thanks!

[jaieger]

Also, I remember reading that Tiffens were inferior quality to other brands such as, say, B+W. Is this true? Because a local store sells a 49mm Tiffen CPL for $50, whereas the B+W one is $100.

[jcob]

To be honest, 3 seconds is about what I'm looking for, so that sounds pretty decent to me. Thanks!

I should probably mention, though, that I had to stop down the aperture all the way. I was doing a test of my daylight long-exposure setup to see if I could get movement in clouds but I don't think 3 seconds is long enough for me (there was barely any wind, though).

Also, I remember reading that Tiffens were inferior quality to other brands such as, say, B+W. Is this true? Because a local store sells a 49mm Tiffen CPL for $50, whereas the B+W one is $100.

I'm not too sure about the quality between different brands. I've only used Hoya filters and I haven't had any problems as far as I can tell (I think the 52mm CPL I got was about $45, if I remember correctly). I'm still fairly new to DSLRs so I don't know if I would be able to pick up on quality of filters as much as others would. But just from what I've seem, B+W filters seem to be popular so I would assume that they are higher end filters (especially since they tend to be more pricey) and they seem to have a better build quality than other brands. Definitely do some research on the different brands. Sometimes, you have to pay more to get better quality but that's not always the case.

Best of luck, though. Long exposures are quite fun to play around with.

[Russell-Evans]

Also, I remember reading that Tiffens were inferior quality to other brands such as, say, B+W. Is this true? Because a local store sells a 49mm Tiffen CPL for $50, whereas the B+W one is $100.

Every manufacturer makes multiple products at multiple price points and because of this, you can't generalize across brands.

Polarizing filters test - Results and summary - Lenstip.com

Thank you
Russell

[newarts]

When you rotate two polarizers with respect to each other the field darkens. As the field becomes very dark it may acquire a blue or red tint depending on material details.

Do not let this tinting worry you; there are many stops of darkening available before tinting becomes a problem.

A circular polarizer should be stacked first to a DSLR's lens; the polarizer stacked atop it should be a linear or a reversed* circular polarizer.

If both polarizers in a stack are circular, there will be minimal effect on decreasing the relative brightness of reflections, sky, etc..

Dave in Iowa

* use a reversing ring or remove the polarizer's glass element, reverse it, and replace it.

[panoguy]

http://www.lightcraftworkshop-shop.com/

It's the "two polarizers stacked" idea, but very well made and has a flared construction (wider filter on the front) to avoid vignetting even with wide-angles lenses. Highly recommended!

[wjjstu]

Some cheaper neutral density filters may not be neutral and add casts or strange tints to your images. I have learned this first-hand.

[Russell-Evans]

I measured my CPL filters and they come out to a 1.5 stop difference in exposure. I'm not sure 1.5 stops is really going to give that much a difference in shutter speed. I think the best you can hope for outdoor daylight shooting is an EV 10 environment where at ISO 100 the slowest speed would be 1/2 a second at f22. With the CPL you might get 1 second on the rare occasion you do find an EV 10 scene.

Thank you
Russell