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View Full Version : Circular polarizer lens: best use?



bonni
09-25-2005, 11:14 PM
I've gotten myself a circular polarizer lens and was experimenting with it today with my Kodak z740. All of the test subjects I chose (granted, it was stuff you could see from the back deck) didn't seem to show much difference in the "with" and "without" versions. I wasn't actually expecting huge differences, but there were almost no appreciable differences in any of them.

I know that a polarizer is useful when taking a picture with a lot of specular lights, such as water (but there's no water viewable from my back deck, heh), but under what other circumstances is a lens of this sort useful?

It's very overcast today with very flat light, so I suspect that's got something to do with why there was no real difference, but I admit I'd like to know more about using a polarizer lens appropriately.

Thanks. :)

bonni

Norm in Fujino
09-26-2005, 01:06 AM
It's very overcast today with very flat light, so I suspect that's got something to do with why there was no real difference, but I admit I'd like to know more about using a polarizer lens appropriately.

To see the difference, merely hold the filter in front of your eye as you view a scene; rotate the filter and see how it darkens/lightens. Especially on days with bright sun, look at some green leaves with sun shining off of them. You'll see how it softens the highlights on the leaves, something you may not have even noticed without the filter. The secret is that you have to rotate the filter on the camera to find the best position for subduing the highlights. Another thing to beware of is your main lens. If the front lens element rotates as you zoom or focus, it will rotate the polarizer with it, throwing off whatever polarizer setting you might have previously decided on. When using a polarizer on my digicam with evf, I couldn't see much change through the viewfinder itself, so I often had to remove the polarizer and turn it in front of my eye manually, decide what the orientation should be, then screw it back onto the camera and rotate it to the same orientation.

bonni
09-26-2005, 08:36 AM
My understanding was that a circular polarizer doesn't have the same kind of "turning" properties that a linear one does. Am I incorrect in that?

Oh, and I have experimented with polarized sunglasses, turning them sideways and such. Those are linear, though, of course...

bonni

Norm in Fujino
09-26-2005, 10:15 AM
My understanding was that a circular polarizer doesn't have the same kind of "turning" properties that a linear one does. Am I incorrect in that?



My apologies; the "turning" kind is the only kind I have. I just did a google on the net for "circular polarizer" and "linear polarizer" and I realize the issues are more complex, although I found a couple of sites that indicated that the "turning" properties were the same with both types. For example,

"Q. My Polarizer has a rotating ring. Is this a circular Polarizer?
Not necessarily, this is a rotating mount polarizing filter. You rotate the Polarizer to achieve the desired amount of polarization."

Actually, I need to get a new one for a couple of my lenses. To the store this weekend!

emalvick
09-26-2005, 11:06 AM
Circular Polarizers aim to have the same results as linear polarizers although the means to get those results is slightly different.

Linear polarizers work by shifting light in one direction only while circular polarizers will shift the light in multiple directions. Rotating each polarizer changes the direction(s) the light is shifted thus you get different results depending on the rotation. The physics are easier to understand with linear polarizers, and you can see the control much easier with a linear polarizer.

However, both types are controlled by rotating the filter to control how much reflected light is getting into the lens. Circular polarizers were only created to deal with problems that autofocus systems had with linear polarizers.

In the shot described earlier, it is unlikely a polarizer would do much good. They are more useful for bright sunny days when you need to remove glare off of water or to help darken the blue sky. I use it sometimes to remove reflections off of glass. I like to photograph old houses and that can be useful. I also find polarizers good for taking photos of things underwater (such as in tidepools), in aquariums, and through windows when small reflections are interfering from an otherwise clear photo.

Erik

Kenyada
09-26-2005, 04:01 PM
Are the premium circular polarizers ($175+) that much better than the cheaper versions ($75)?

ReF
09-26-2005, 05:39 PM
Are the premium circular polarizers ($175+) that much better than the cheaper versions ($75)?

usually the higher costs have something to do with the coatings on the filter. the coatings prevent flare. some filters have more coatings than others while some have an anti-scratch coating over flare-cutting coatings. B&W supposedly make the best coated filters in general but at a premium (plus they just cost more in general), and don't offer the wide angle, low profile versions like Hoya.

remember use a hood with your filters!

bonni
09-26-2005, 05:41 PM
However, both types are controlled by rotating the filter to control how much reflected light is getting into the lens. Circular polarizers were only created to deal with problems that autofocus systems had with linear polarizers.

Ahh. Gotcha.


In the shot described earlier, it is unlikely a polarizer would do much good.

That's what I figured.


They are more useful for bright sunny days when you need to remove glare off of water or to help darken the blue sky. I use it sometimes to remove reflections off of glass. I like to photograph old houses and that can be useful. I also find polarizers good for taking photos of things underwater (such as in tidepools), in aquariums, and through windows when small reflections are interfering from an otherwise clear photo.

Thanks, that's the sort of thing I was wanting to know. I knew about the sky/clouds, but wasn't sure where else would be a good candidate for a polarizer lens. One good thing appears to be that even if it's not necessary, it doesn't really detract from the photograph if you use it, so that takes a bit of the guesswork out for me.

Now I have a good excuse to go for a trip to the coastline, hehehe. ;)

bonni

tim11
09-26-2005, 07:18 PM
Just a question re. polarizing filter.
Do you have to re-adjust the angle for the next shots? (I mean whenever you frame a new subject with different locations and different angle to the sun to the previous one).

emalvick
09-27-2005, 07:57 AM
Just a question re. polarizing filter.
Do you have to re-adjust the angle for the next shots? (I mean whenever you frame a new subject with different locations and different angle to the sun to the previous one).

If you need the effects of a polarizer, you do have to readjust it from shot to shot. It may not be totally necessary, but usually. At least, I tend to adjust it. For all I know, I may often end up back at the same angle.

Now, if you don't adjust the filter, it won't hurt anything in terms of the photo. It just may not be optimal. As Bonni aluded to, a polarizer doesn't hurt when it isn't needed, although it does reduce the f-stop of the shot because it slightly darkens the lens. In darker situations I do remove the polarizer to let more light in, especially as I get into that area where I need a flash or slower shutter speeds (unless I want the slower shutter speeds).

Erik

Robert Besen
09-27-2005, 06:21 PM
I read an article in "Outdoor Photographer", I believe, that suggested trying other angles than the one that darkens the sky the most; improved saturation in foreground objects, for example, might be improved with a different polarizer angle. The nice thing about digital is it's so easy to experiment.

bonni
09-27-2005, 06:56 PM
I had fun yesterday, which was a very bright, sunny day. I took my kids to the playground and brought the camera along and played with the polarizer lens to see what would and wouldn't work, etc., but pretty early on I realized I was wearing polarized sunglasses, and when I'd turn the lens (or the camera) it'd get really dark in a hurry... LOL!

Naturally, I had to take my sunglasses off, and I did get a few really good pictures and a lot of mediocre ones (which is usually the way when taking photos of kids playing, in my experience).

I probably didn't strictly need the lens for most of the shots, but it was fun to play with it.

So, lesson learned: take off your sunglasses before you look through the viewfinder! :D

bonni

emalvick
09-28-2005, 07:53 AM
You know, when I am out on a really bright day, especially when I am hiking, I usually put the polarizer on the camera and leave it there all day. It is always possible to turn the polarizer so that it has no effect (other than abit of darkening).

I also have to agree with the post by Robert Bensen about not using the setting that darkens the sky the most all the time. Sometimes I find that darkening the sky that much makes the photo almost look fake. This is especially the case on a clear day. The foreground will almost pop out from the sky in a very weird way. Using a little less on the polarizer will fix that problem and can help with the foreground too.

Erik

ReF
09-28-2005, 06:55 PM
another thing to note is that on really wide shots, polarizing at max can cause one portion of the sky to look much darker than the rest - an effect than isn't particularly pleasing. this can also become a problem if you don't readjust the filter when turning to face a different direction.

Norm in Fujino
09-28-2005, 08:58 PM
All this talk reminded me that I didn't have a polarizer filter for my two main lenses, so I dropped by Yodobashi's on the way home from Tokyo yesterday and picked one up. It's a Kenko Pro1 Digital Wide-Band Circular--I haven't researched the various brands so don't know what differences they may have, but here's a shot I just took outside my veranda. Bonni should notice the greatest effect by trying a shot with lots of blue sky. Even then, the effect can be subtle as you rotate the filter. It also helps, once you've located the position with greatest lightening or darkening to take note of where the label or imprinting on the filter is located; turning it 90 degrees from that point should produce the opposite effect.
--Also, as illustrated by this photo, you have to be careful when you have a filter installed especially with wider angles due to the potential for vignetting (lower right corner). This disappeared on a subsequent shot at 17mm.

http://www2.gol.com/users/nhavens/resource/P9292810_1a.jpg

Oly e-300 + ED 14-54 (14mm), f5.6@1/160, ISO 100 + Silkypix 2.0

bonni
10-02-2005, 02:03 AM
Cool. This is all very intersting to me. I've been experimenting with my polarizer more, including on a bright, sunny day. I really, really need to go to the seaside and take some pictures there. I think having polarizer will be a great asset in that case. :)

bonni

Norm in Fujino
10-02-2005, 06:12 AM
Cool. This is all very intersting to me. I've been experimenting with my polarizer more, including on a bright, sunny day. I really, really need to go to the seaside and take some pictures there. I think having polarizer will be a great asset in that case. :)


A couple of tips I found on other sites:

"Maximum polarizing effect is achieved looking 90 away from the sun (i.e. your shoulders in line with the sun). If you are shooting into the sun or 180 away from the sun you will see no polarizing effect."

Another way this was explained was as follows: hold your hand with index finger pointing out and thumb pointing up (like a gun). Then point your thumb at the sun. The maximum polarizing effect will be found along the arc traced by your forefinger as you rotate your hand around the axis of the thumb.

A good site giving practical advice and examples:
http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/polarizer.html

bonni
10-02-2005, 07:14 AM
Excellent link! Thanks!

bonni