Polarizer vs neutral density

d40bby · Apr 24, 2009

I recently took some waterfall shots for the first time when I was out hiking. I experimented with shutter speeds etc, just trying to get the different effects you can get with the moving water.

When I got home and reviewed the shots, I noticed that there was a lot of glare coming from random places (it was a little sunny out) that I felt distracted from the shots.

I've been reading "understanding exposure" (a great recommendation from this forum :thumbup

and Peterson mentions using a polarizing filter in situations like this.

Well, I went to the store to grab a polarizer, and after telling the girl why I wanted it, she said "That's not what you want, you want a neutral density filter." She said it would help smooth out the waterfall shots. The packaging for the filter even had a side by side comparison shot of waterfalls. (it was a sunpak platinum plus filter).

Long story short, I bought both of them, but I was wondering which one is REALLY the one I want to use. I guess I'm just having trouble understanding the true difference between the two.

Which filter do you guys use for waterfall shots and why? I appreciate the input!

prodigy2k7 · Apr 24, 2009

Eh... They do similar things, but do different things...
Polarizer is for, bluer skies, take reflections off non-metalic items, a ND just cuts down on the light itself. A ND filter would help because it would allow you to use a longer shutter (for sikly water, instead of frozen water)

A Polarizer does make the scene slightly darker so in the way, its like a ND filter, but not the same...

d40bby · Apr 25, 2009

hmmm ok. thanks for the reply

dxqcanada · Apr 25, 2009

What do you mean by glare ?

A Neutral Density filter is designed to reduce the amount of light entering the lens without affecting colour and contrast. This allows you to shoot with slower shutter speeds (ie to obtain motion blur of the water).

A Polarizing filter is used to filter out light of a particular polarization. As light is reflected off an object it can be polarized to a specific direction. A polarizing filter allow light of a specific polarization (direction) to enter the lens and blocking the rest ... so as you turn the filter you will see that some reflected light disappears.
This is good to reduce light reflection off of leaves, water, and the sky. Due to it's design it also will reduce some light from entering the lens.

dcclark · Apr 25, 2009

If you are having trouble with light glinting off of water, then it may get worse with long exposures. In that case, you definitely want a polarizer to help.

When I'm out waterfalling, I almost always either (a) go on cloudy, overcast days to avoid glare, or (b) bring a polarizer for good measure.

benhasajeep · Apr 25, 2009

Which polarizer filter did you get? Did you get a circular or linear? A circular polarizer is what you want. You turn it to acheve the desired effect. It goes from full effect to none within a 90 degree turn. Using it propperly you should not be getting alot of glare, unless thats the effect you wanted.

They can be used together as well.

LarryD · Apr 25, 2009

Were you using a good lens hood....

You have to choose one or the other filter (well, you don't HAVE to, but you know what I mean).

With a Polarizer, you lose about a stop of exposure, so it can substitute for a poor mans ND but is designed to reduce reflective glare. It will not stop lens flare or glare that is not aligned with the polarization of the filter...that is why it is rotatable.

The ND will only darken the scene, allowing you to expose for longer periods........this effectively blurs the moving water (making it softer) but it does absolutely nothing for any reflective glare that is there.. ND's are available in a number of different strengths so if you're going to get one, get one that will do the job - at least 4 stops, maybe more.

Both are good to have in the camera bag....... but each is used for a slightly different effect.

dcclark · Apr 25, 2009

benhasajeep said:
Which polarizer filter did you get? Did you get a circular or linear? A circular polarizer is what you want. You turn it to acheve the desired effect. It goes from full effect to none within a 90 degree turn. Using it propperly you should not be getting alot of glare, unless thats the effect you wanted.

They can be used together as well.

He wants a circular polarizer, but not for this reason. Linear polarizers mess with autofocus systems (which already use linear polarizers to help focus). There is no difference between linear and circular polarizers in terms of reflection reducing.