Circular Polarizers? How do I use it?

[zohar0]

Hello, I just bought a CPL off BH and got it in the mail, how do I use it on my 18-55mm ? I put it on and dont understand what to do, I twirl it around and it makes the sky darker greyish, not really darker blue which I see online.
If you want to see what im talking about i'll take pictures in the morning.
I am leaving saturday night on a trip to take landscapes so would be nice if I could get an answer =)

Thanks!

(My Filter) (http://www.bhphotovideo.com/c/product/22704-REG/Hoya_580191_58mm_Circular_Polarizer_Glass.html#fea tures)

[goldboughtrue]

You do twist it to change the effect. If the sky is clear blue or blue with puffy clouds then you'll see a big difference, but if it's overcast then it doesn't do any good. The polarizer makes a difference when you're 90 degrees from the sun. In other words, it has no effect if you're looking at the sun or directly away from it. The polarizer is also useful to reduce glare off windows or water.

[argyle]

What the previous poster said. A polarizer will not magically turn a 'blah' sky blue...it needs to be blue to start with. When you say that it made the sky dark grayish, what was the sky like before you put the filter on? Also, what brand is the filter? If the conditions aren't correct, all you're doing with a CPL is knocking down your light by nearly two stops.

[SkipD]

A very important tip:

If you are using the filter without a lens hood (so that you can reach the filter's rotating ring) and rotating the filter while looking through the camera, MAKE SURE YOU ONLY TURN IT COUNTER-CLOCKWISE (relative to looking through the camera). That way it won't come off the lens and drop to the ground unexpectedly.

In Britain, I believe the term is "anti-clockwise".

[zohar0]

Here is an image with the sun directly to my right.
It looks pretty horrible because the sky is very very uneven in lightness and darkness.
I know my sensor is dirty, I don't know what to do because my rocket blower wont fix it and I dont want to ruin the sensor or pay $100 to have someone do it =P

WithPolarizer 1:
http://img220.imageshack.us/img220/570/img3033rf3.jpg (http://imageshack.us)

With Polarizer 2:
http://img371.imageshack.us/img371/173/img3034ca9.jpg (http://imageshack.us)

Without Polarizer:
http://img526.imageshack.us/img526/1619/img3035yj2.jpg (http://imageshack.us)

[zohar0]

I thought the polarizer would help me brighten the ground and then darken the sky, the images I showed you, the ground just looks dark, whats the problem?

[Balliolman]

The polariser works best if used 90 degrees to the sun (sun on your left or right side).

[zohar0]

Yes, the sun was to my right side..

[argyle]

I thought the polarizer would help me brighten the ground and then darken the sky, the images I showed you, the ground just looks dark, whats the problem?

A polarizer will not balance the exposure when you have a bright sky and dark foreground. What you need to do this is a graduated neutral density filter, or 'GND' for short.

The GND is tinted on its upper portion and clear on the lower portion. They're available in different strengths, as well as the type of gradient edge (hard or soft). Since they're clear on the bottom, this will allow you to knock down the exposure of the brighter sky without affecting the darker foreground, thereby balancing out the exposure. The polarizer (as well as ND filters) are solid (i.e. no gradient) and will affect the entire image. The polarizer can also be used in tandem with the GND.

[zohar0]

But what I want is darker skies, how do I get that with bright foreground?
For example in this photo (I did not take this) i'm guessing they used a polarizer. See how the valley is very bright and looks great and the sky is not blown out, this is what I want and how may I do this, sorry.
Yosemite (http://www.desktopscenes.com/Scenes%20from%20a%20Day%20at%20Yosemite%20(2003)/Yosemite%20Valley%20Tunnel%20View%20Panorama.jpg)

[Snow001]

The polarizer can also be used in tandem with the GND.

I personally love landscape shots and hopefully one day I can take a shot that might come close to the Yosemite shot above. I recently purchased a B+W Kasemann to use with my Sigma 10-20. If I get the Hitech NB Grad 0.6 SL and attach this using a Lee 4x4 Professional kit, would this be the way to start in terms of filter equipment in hopes of trying to come up with my goal?

Thanks in advance

[SkipD]

But what I want is darker skies, how do I get that with bright foreground?
For example in this photo (I did not take this) i'm guessing they used a polarizer. See how the valley is very bright and looks great and the sky is not blown out, this is what I want and how may I do this, sorry.
Yosemite (http://www.desktopscenes.com/Scenes%20from%20a%20Day%20at%20Yosemite%20(2003)/Yosemite%20Valley%20Tunnel%20View%20Panorama.jpg)T he "problem" with your images is the fence that is totally shadowed.

Darkening a plain blue sky (like in these images) is not necessarily a good thing for the composition. Darkening the blue of the sky behind white puffy clouds, on the other hand, adds something significant to the composition.

[zohar0]

Okay.. And what about if the sun is directly above me, how do I do the 90 degree thing?

[neil_r]

I have just bought a Bell 407 Jet Ranger helicopter, how do I fly it?

[argyle]

But what I want is darker skies, how do I get that with bright foreground?
For example in this photo (I did not take this) i'm guessing they used a polarizer. See how the valley is very bright and looks great and the sky is not blown out, this is what I want and how may I do this, sorry.
Yosemite (http://www.desktopscenes.com/Scenes%20from%20a%20Day%20at%20Yosemite%20(2003)/Yosemite%20Valley%20Tunnel%20View%20Panorama.jpg)

Like I said...you need to use a graduated neutral density filter. This will prevent the sky from getting blown out. A polarizer can be used with the GND as well to bring out the sky effects that everyone's so fond of.

Below is a picture that I shot at Havasu Canyon. The cliffs were in total afternoon sun, and you can see a glint of sunlight on the upper cliff from the late afternoon sun. This was also the only day that had some clouds present in the sky. To balance the exposure between the sky and the lower portion of the frame (without losing the detail in the cliffs),I used a 3-stop GND. To bring out the sky/clouds, I also used a circular polarizer (to help the sky and control reflections on the water) with the GND. The 3-stop GND balanced out the exposure by preventing the cliffs from getting blown out, and also allowed me to capture the last bit of glint on the upper edge of the cliff.

http://northlake.smugmug.com/photos/302580177_8b4LC-XL.jpg

You can also take two exposures of the scene, provided that your camera is mounted on a tripod. Take one exposure for the sky, and the second for the foreground. Then, blend them together with layer masks in Photoshop.

There's more to using filters than just sticking them on the front of the lens and firing away...you need to know what effect a particular filter can provide, know when to use them and, more importantly, HOW to use them. There are plenty of resources available on the internet...do a search and then do a lot of reading. Here's a link to get you started...just pay particular attention to the polarizer, neutral density, and graduated neutral density filters...the rest of the info isn't really applicable to digital photography:

Link to filters and their usage (http://www.bythom.com/filters.htm)

[Balliolman]

I have just bought a Bell 407 Jet Ranger helicopter, how do I fly it?

Point it at the sky! :p :D

[sapearl]

Zohar - this is a classic problem that many photgraphers often run into..... happens to me all the time in situations with extreme contrast differences betweeen bright sky highlight and deep foreground shadow.

As others have pointed out, the CPL works best when you are at 90 degrees to the sun. But you also pointed out that part of your sky goes dark, while a portion is lighter. This is pretty typical when using a CPL on an UWA or pretty wide angle lens. The lens is taking in such a huge area of the sky that the CPL is taking in "90 degree rays" as well as those of a much lesser angle as things fan out towards the edges. The darkenning will therefore be less. The way around this is to use not such a wide angle, or "dodge" and "burn" in PP. I will do this a lot with my prints.

But what I want is darker skies, how do I get that with bright foreground?
For example in this photo (I did not take this) i'm guessing they used a polarizer. See how the valley is very bright and looks great and the sky is not blown out, this is what I want and how may I do this, sorry.
Yosemite (http://www.desktopscenes.com/Scenes%20from%20a%20Day%20at%20Yosemite%20(2003)/Yosemite%20Valley%20Tunnel%20View%20Panorama.jpg)

[sapearl]

Ok Zohar, examples speak louder than words so I will try to show you what I mean along with a possible solution. Please consider the picture below. When I shot this early in the morning my mind's eye saw a bright sky with beautiful cloud detail and the wispy threads of smokestack contrails.

At the same time, I saw some beautiful gray textural tonality in the foreground shadowed slag piles. Problem is they are pretty dark compared to the bright sky. If memory serves me, there was probably about a 5-stop difference in brightness between the two. How do you address that?

Some people shoot HDR with a tripod, some use GND filters.... both very valid techniques that will get you fine results. I'm too lazy for that.

Instead, I will pretty much meter for the highlight ("shoot to the right") after twisting my CPL to give me the most pleasant sky/cloud contrast. I also shoot in RAW and use ACR so I have the maximum amout of information to work with, and also "recover" in post processing.

=>

[sapearl]

In the picture above, I shot and for the sky/cloud highlights, knowing in advance that I would have to attempt to recover the shadow detail in post processing in CS3. It is extremely difficult if not impossible to have the camera capture EVERYTHING as the human eye/perceives the scene. Sensors are just not good enough yet. Film is generally superior in it's ability to capture the tonal range but it still can't get it all.

I created this final 13x19 exhibit print by using exposure adjustment layers in CS3. I first post processed the sky to where I wanted it. And then I created a duplicate layer for the work I'd do on the shadowed foreground. I then went to IMAGE ==> ADJUST ==> EXPOSURE, and increased the slider about 2 stops. Any more than that and the image takes on noise, unpleasant contrast, saturation..... just plain looks wierd.

When the above was done, I created a LAYER MASK to HIDE ALL, and then proceeded to "erase away" the mask over the shadowed foreground, increments, letting detail through until I was pleased with the results. Above is the final product. Hope this helps - let me know if you have any further questions. - Stu

[piku]

Nice. Thanks for the informative post @sapearl.

[zohar0]

Thankyou guys for the great examples included with the helpful posts. This really helps me understand how it works. I just got back from a two day vacation and was reading your posts and they greatly improved some landscape photos I took. THANKS!

[sapearl]

Glad we could help zohar - hope you had a nice little vacation there :D. If you'd like to see more examples of shots done with a CPL, check here:

http://www.pbase.com/sapearl/cleveland_flats

Almost all of these were done with the CPL, as well as a fair amount of PP work. The main lens was the 24-105 on the 5D, although I used the 17-40 for a number of them. - Stu