12-16-2008, 06:50 PM #1
Polarized vs ND filters.... Please advise!
When I see a good landscape scene with a sky that I would like to preserve it's details I jump immediately and mount my Polarized filter to darken the sky and give some rich effect to the photo.
While in many posts I can see people also recommend the ND to give the sky effect.
Which one would you mount??
12-16-2008, 08:24 PM #2
The polarizer for normal day time shots but when you want to shoot longer exposure shots
and its still pretty much daylight the ND will help keep it from getting blown out.
I use a circular polarizer on all my lenses just so I don't have to change them out and the other benefit is the protection factor.
ND filters I see used most are for the long exposure shots of soft water and the whispy cloud look. Not that you can't use them at other times but you must remember that it will stop it down some. I dont use ND filters so not sure how much it changes the exposure for each size but others who do will probably chime in here to let you know.
12-16-2008, 11:16 PM #3
You know those wicked shots of waterfalls or coastlines that have the water all ghosted?
Those are accomplished with super long (Ie 20-30+ seconds) shutterspeeds. Try doing that during the day without a good ND filter and all you'll get is white.
A polarizer is, essentially speaking, a very weak ND filter that only affects light going in one direction. An ND filter doesnt affect the sky in the same way, though, as it affects light moving in all directions, whereas a polarizer directs the light into one particular direction: it "polarizes" the direction of the light.
Thats why circular polarizers are able to alter their affect: rotating the filter changes the direction of the light. A ND filter has no direction: it just blocks light.
A polarizer is kinda like shooting through a set of blinds, whereas a ND filter is like shooting through a darkened piece of cellophane.
12-17-2008, 12:04 AM #4
Without seeing the posts you are referring to I am guessing what is being suggested here is a Graduated Neutral Density filter rather than the solid color screw on filters.
Graduated Neutral Density filters vary from their solid round counter parts in that they are usually a square piece of glass that slides into a holder fitted at the front of the lens. They also differ in that instead of being a solid density of gray they are a graduated density which transitions, from a clear half to a darker half. This will allow you to darken a bright sky without effecting the exposure of the rest of the scene.
Here is some information on Graduated Neutral Density Filters you may find of use.
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12-19-2008, 08:23 AM #5I'm new here!
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As mentioned above, you would need a graduated ND filter to affect the sky without the foreground. Personally, I never use them, but there is a trick if you have Photoshop:
The best way to do this is while converting the RAW file if you have CS3. Just go to the HSL sliders, and reduce the luminosity and increase saturation for blue. This darkens the sky without affecting the clouds, so gives more dramatic skies.
The above is useful if you have overblown grass and foilage in the foreground, but you need to adjust Yellow for that.
Once open, and this works in much earlier versions of PS, you can do the same thing with a Selective color adjustment layer by increasing the Black slider for Blue and Cyan, (as well as Yellow for grass etc).
If you have LR2 or CS4, the graduated adjustment feature is simply amazing, and seems to be capable of huge adjustments without introducing too much noise. (I am talking about 1DsMK3 files here, so I'm guessing that makes a difference).
BTW CPFs have their biggest effect at 90 degrees to the direction of the sun. It's one of those givens, like rainbows MUST be opposite the sun from where you are viewing. A very high sun (midday) means you get a much wider effect, because much more of the scene is at or near to 90 degrees.
Last edited by Trevor.Dennis; 12-19-2008 at 08:33 AM.
12-19-2008, 05:44 PM #6I'm new here!
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Well I use both, I use a polariser to deepen the colours of the scene in general, and eliminate reflections, and seeing I always expose a landscape for the foreground, I also use an ND grad to stop the sky being overexposed. Shutter speeds can get pretty slow, but when I shoot landscapes I always tend to use a tripod anyways
just my 2 cents worthI blog at smashandpeas.com
12-22-2008, 09:13 AM #7
Polarizers are good for reducing glare and revealing detail in water, enhancing the saturation of blue skies, and are really only effective when the sun is in certain positions. Not worth a cracker if you need to stop down or have sky/water detail that would normally blow out. The best type is Circular but you can also get other types such as cokin.
ND's filters come in several types and grades. Graduated is probably the most useful as you can use it to reduce the light recieved in the area that would blow out and yet keep correct exposure for the rest of the image. ND's come in 2,4 and 8 (I think that this equates to stops of light), and I normally work with 2 and 4's. The ND works well with grey cloud detail and is used a lot in landscapes. I use graduated P-cokin filters but also have a Circular one that fits the cokin mount.
12-30-2008, 07:02 PM #8dPS Forum Member
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