Noob question.... when do you use a polarizer?

[AMDnut]

OK, last night I was practicing with my S2, taking action shots as the kids got new bikes. The sky was partly cloudy, so I wanted to play with the new polarizer filter that I have. It was early evening, around 7:30 and I wanted to see what a difference it would make. I shot a normal "landscape" shot (P mode) at EV0 with only the UV filter. Then, I attached the polarizer and shot same scene..... and I don't really see a difference! There is a small change, but not as much as I thought there would be. The scene had both green grass, trees, blue sky, and nice clouds.

So, question is, is there a time that the polarizer filters really work best? Like full brighter sun where the sky is washed out and white? I know I need to do more tesating, but is there a real "general" rule of thumb for when you pull out the polarizer?

Thanks!

[GaryS]

Polarizers are trickier to use than most filters. Give this a read...

Info about polarizers (http://dpfwiw.com/filters.htm#polarizers)

When shooting skies, they work best at 90 degree angles to the sun. The closer you are to shooting at the sun (or away), the less effective they are. And even when shooting at 90 degreees, you still need to rotate it while watching your LCD or viewfinder to watch when the polarization takes effect. I always lock depress the shutter half way, then rotate the polarizer until you can see the effect, then release the shutter and depress again.

They are kind of fiddly, but they can really improve SOME shots.

[DonSchap]

It has been my experience that a polarizer is used when light is bright and can be rife with reflections and haze. The filter "cleans up" the image by filtering out stray reflections. Whenever I am taking shots, outdoors, the CP is fitted on the lens.

A polarizer only allows light to travel in one plane, rejecting any coming in from another. By doing so, it improves color and eliminates reflections. If you are shooting water, adding a polarizer and adjusting it will allow you see what's below the surface... eliminating the sunlight reflecting from the surface. This an excellent use for seeing those sneaky fish and rocks below.

For dramatic skies, it increases the contrasty look of cloud formations and can deepen the blue of the sky itself. If you are going to have a sky behind your subject, the polarizer will give you back the clouds you would normally lose to glare and the bright intensity.

One thing to be cognizant of is that a 'poor' polarizer can really mess up your autofocus (AF), especially at long focal lengths. I have a $25 86mm CP that totally destroys the AF capability with my TAmROn SP AF200~500 f/5-6.3 Di LD. You put it on and you are using your eyeball as the focus determination device... and at 500mm... that isn't good with a 20D, as there is no MF screen built-in. Bottom line, here: Don't be afraid to invest good money in a good polarizer for a good lens. Putting a $100+ polarizer on a $80 lens doesn't make any sense, either, unless it also fits a far more expensive lens that you already own.

Unless you are using a creative filter set, polarizers and other screw-on filters are usually "cut-to-fit" devices. That means, they are specific to ring size, so that if you have more than one lens (basically, this applies to the SLR crowd) ... chances are you will need a different-sized polarizer for it. These additive costs can be substantial. An investment in 'filter adapting rings' might be in order. These low cost devices can reduce an 82mm filter or 62mm down to a 52mm in a couple steps... or you can spend the extra dough and get one that does it all at once. Ofcourse, there are all sorts of side issues with this steeping down (lens hoods don't fit; it looks a bit awkward; etc.), but what do you want, good looking photographer or good looking images... with unspent coin in your pocket? At $100+ per filter, this can be a serious investment for all your different-sized lenses. Filters are not a fashion statement.

How much can a filter run? An 86mm B+W Kaesermann CP (circular Polarizer) is around $215. You really only want to buy one of these beauties... but by buying it LARGE... you can use it on all your smaller lensing with adapters. Going small and using the rings to make it fit a larger lens will have you vignetting everything (kind of like looking through a black, fuzzy hole). You can figure around $100 for a good B+W multicoated circular Polarizer.

Try to remember this, about polarizers: You can not simulate the elimination of reflection with Photoshop. They are a solid investment in improving what you see, real time, with your camera. ;)

BTW: There are also color-shift polarizers, which can, depending on how the light hits the filter, cause a color-shift in the subject. You can have a lot of fun with these type of filters, literally changing colors on the fly as you click away. They can make a rather lack-luster image vibrant and quite intense. These definitely for the 'experimentalist photographer', as they offer enhancement, but also require some additional time to... "GET THE SHOT!"

[ReF]

other than what was already mentioned, especially the part about max effect at 90 degrees to the sun, a polarizer doesn't deliver a noticable effect in all conditions. it really depends on a lot of thing such as lighting conditions, angle of the light, angle which you are shooting, time of day, subject matter, etc. you can always hold it to out and rotate the polarizer to see if there is any effect before putting it on. sometimes when using a live preview camera the camera will automatically adjust to the polarizing effect and therefore you may not see much of a difference on the LCD. this might make you want to take two or more of a shot to compare later, which can be time consuming, so eyeballing the difference with the polarizer in front of you first may help.

[coldrain]

Here an example where the sky is a bit pale to start with due to a cloud haze. As you can see, the bottom photo shows better defined sky, also the green may seem a bit more green. The filter filters polarized light, and I am too hazy myself to try and explain what that is ;).

When the skies are more clear, the effect can be much more pronounced, you can get skies to go into almost black when wanted, in some situations. Like you are looking directly into space.

[GaryS]

Just to comment on Coldrain's excellent example shots...

Not only is the sky bluer with a nicer run from light to dark going up, but also look how much better lit the building is. Because the sky isn't so bright, the rest of the picture is better exposed....

[XaiLo]

Absolutely you can especially see the difference in the steeple and dome. With the polarizer they no longer appear blown, rather the detail and saturation is clearly visible.

[JTL]

Also, a polarizer will have a noticeable and positive effect on "greens" in those same circumstances. Carefully look at the trees in Coldy's shots and you'll see what I mean...the shadows appear lifted and the trees appear more vibrant with the polarizer...

[AMDnut]

Thanks guys!

Thanks for the link dustyporch, reading it now!

I can see a nice difference in those 2 shots coldrain, thanks! Both sky, details, and greens look great.

That is what I am looking for, but I need to practice more. I was mostly shooting with the sun to my back right, and it was evening. Those 2 things are what eliminated the effect from what I can tell.

Thanks again...

[BowerR64]

Look how the polarizer gets rid of the nasty blury moving vehicles! that alone is worth it!:rolleyes: