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02/04/2007 06:14:12 PM · #1 |
I feel dumb.
I went to take pictures for the "Where I live" challenge today and used my circular polarizer for the first time. I admit, it's a cheap Quantaray circular polarizer but it seemed to really mess up a lot of my shots. When I looked through the viewfinder I turned it so the sky looked darker but the resulting picures are very uneven.
Here's an example straight from the camera (except resized):
Am I doing something wrong? Am I just a hack? Is it that it's a cheap crappy one? Or is supposed to look like that? |
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02/04/2007 06:23:07 PM · #2 |
hey mate ... it's ok. a few people ask this question.
the polarising filter is comprised of two rings. so have a look at the polariser and try turning the outer ring. when you turn it (it should turn all way round) it will adjust the polarising effect. make the shot darker or lighter.
you need this adjustment depending on the amount of light and glare.
one handy trick is that you can use a polariser to cut through the glare and see straight through water ... point your camera at some water, turn the outer ring, hey presto! you can see da fishies!!
beware of a few things. polariser makes your shot darker, so it's equivalent to stopping down your aperture 2 or 3 steps.
also, if you use a UV filter and a polarising filter together, you run the risk of vignetting ... especially on wider angle shots. **look in the top left corner of your shot, there's a little vignetting creeping in there! :)
hope that's helpful! :)
Message edited by author 2007-02-04 18:23:47.
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02/04/2007 06:25:38 PM · #3 |
Originally posted by super-dave:
one handy trick is that you can use a polariser to cut through the glare and see straight through water ... point your camera at some water, turn the outer ring, hey presto! you can see da fishies!! |
So it doubles as a fish finder?
*Art grabs his fishing pole and polarizer and heads to the lake* |
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02/04/2007 06:31:01 PM · #4 |
Yeah don't feel stupid, we're all learning right?  super-dave is right; I think the problem you're having in that shot you posted isn't caused by you or your polarizer, it's from our lovely friend the Sun. I've noticed that depending on it's angle in the sky relative to where you are at you'll get a nice gradient from light to dark; dark to light etc..
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02/04/2007 06:32:04 PM · #5 |
Originally posted by Art Roflmao:
So it doubles as a fish finder? |
LOL ... i'd never thought of that!!
i've done it in ponds and stuff, but never in bigger rivers or the ocean. you can see surprisingly far into the water when you cut away the glare.
*grabs fishing gear and camera ...
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02/04/2007 06:34:07 PM · #6 |
First, you don't specify what the focal length was here, but it looks very wide. Polarization of the sky is maximum at 90 degrees from the sun. in your shot, the sun is low and on your left, and the stripe of heavy polarization is right where it should be, running just right of center.
This is normal behavior for a polarizer on an ultra-wide lens. You can make it appear more even by carefully composing to only include the darker sections, but you may find you need to use a longer focal length. An alternative is to use the natural "gradient" to compositional advantage.
FWIW, the vignetting at upper left is probably a result of either two stacked filters, or the lens is *so* wide that even the one filter is beginning to intrude into the frame. |
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02/04/2007 06:38:44 PM · #7 |
As the name implies, this filter permits transmission of light in only one plane of polarization. So you are rejecting all the light that is not polarized at the angle the filter is set. Sunlight is always polarized by the atmosphere and then scattered by clouds, reflections from the earth, etc. The polarizing filter is intended to reduce or eliminate glare from reflective surfaces that have a unique reflected polarity.
The uneveness of the sky color in your example photo is caused by the angle of the sun with respect to your subject. At some angles, this uneven effect is more pronounced, such as 90 degrees to the sun. Shooting directly away from the sun produces a much more uniform effect. |
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02/04/2007 07:05:45 PM · #8 |
... erm now I feel dumb ... I did not think that turning a circular polarising filter did anything. I did not even think you could turn one without screwing it tighter or looser on the lens.
P.S. The photo that started this thread DOES look like he was using a circular polarizing filter ... as in with concentric circles of ... erm ... "lines" rather than parallel ones.
Message edited by author 2007-02-04 19:09:25.
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02/04/2007 07:08:18 PM · #9 |
Originally posted by Greetmir:
... erm now I feel dumb ... I did not think that turning a circular polarising filter did anything. I did not even think you could turn one without screwing it tighter or looser on the lens. |
there are two rings ... once you screw it on to your lens, the outer ring should still be adjustable.
my polariser's outer ring has a gauge on it, so that i know what level of polarisation i'm using! :)
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02/04/2007 07:15:47 PM · #10 |
What we gotta figure out here is if he as a round linear polarizing filter with two rings or a round circular polarizing filter with one ring. //www.thkphoto.com/products/hoya/gf-04.html for some info ... I don't thing circular polarizing filters adjust by turning them ...
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02/04/2007 07:21:31 PM · #11 |
i have 3 polarising filters and they all have two rings to adjust the polarising effect.
i actually assumed that they were the most common type! LOL
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02/04/2007 07:26:33 PM · #12 |
Here are two shots with the polarizer turned between photos. (My membership expires tonight, so you may not seem them after server midnight, but I will renew middle of the week)
 
Absolutely no adjustments made. Straight from the camera, resize for web only.
Message edited by author 2007-02-04 19:27:26. |
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02/04/2007 07:26:45 PM · #13 |
Polarizers are used for several things:
1-Remove polarized light to get a clearer and more detailed image, especially in images with reflected water and sky.
2-Deeper and richer colors and greater clarity at higher altitudes where polarization has a great effect on the appearance of images.
3-For greater and more pronounced tonal changes for images intended primarily for B&W.
4-To act like a neutral density filter to allow for longer exposures when desired.
Message edited by author 2007-02-04 19:39:27.
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02/04/2007 07:33:50 PM · #14 |
Hello? ... a linear polarizer is the most common ... it has straight parallel lines in it like a venitian blind ... a CIRCULAR polarizing filter has lines in concentric circles and turning does diddley!
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02/04/2007 07:46:04 PM · #15 |
Originally posted by Greetmir:
Hello? ... a linear polarizer is the most common ... it has straight parallel lines in it like a venitian blind ... a CIRCULAR polarizing filter has lines in concentric circles and turning does diddley! |
For a digital sensor camera ya need to use a Circular Polarizer filter not a "Straight" one. The focus will be degraded with a straight. AND yes Cir Pol filters do have a rotating ring which allows the filter to be rotated based on need. Film camera do not have an issue with regular polarizing filters. |
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02/04/2007 07:48:02 PM · #16 |
Thanks for the replies. Now I'm not sure what kind of polarizer it is. It has 2 rings, one screws in th the other rotates. I rotated it to make the sky darker. The shot was taken at 18mm so I suspect  kirbic is correct and the unevenness is due to the wide angle of the lens.
There is vignetting on the corners but the polarizer is the only filter on the lens. The Nikon 18-70 really doesn't like to have filters on it at it's widest angle. |
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02/04/2007 07:56:41 PM · #17 |
OK ... finally found the answer. Long search ...
//www.luminous-landscape.com/tutorials/polarizers.shtml
Includes Polarization and Wide Angle Lenses and Circular Vs. Linear Polarizers.
Message edited by author 2007-02-04 20:34:23.
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02/04/2007 09:13:14 PM · #18 |
cutting water glare was mentioned but don't forget the glare from tree leaves and glass. I've used it when photographing cars too although it's a little harder cause of the car angles. I ended up shotting once then rotating the lens to cut glare from another location and shooting again and merging the images to get a clean glare free car.
I love mine, problem is I have a 52mm filter and 52mm and 58mm lenes, gonna have to get one for the larger lens.
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