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Archive 2005 · Polarizer Style
  
 
sbraab
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p.1 #1 · p.1 #1 · Polarizer Style


I moved this from landscape where nobody replied.

So my recent trip to yosemite made it clear that I need to get a polarizer and some graduated ND filters. I will likely get the cokin p system. My question is: Which polarizer do people like best round snap-in, square, or a traditional round screw on model?

I think square is out because I will use it with the grad ND, but there seem like there might be some benefits to having a the traditional screw on model. I am guessing the answer will be to buy both, but with the nice ones costing ~150 usd I won't be buying two anytime soon.

I really thought you could just PS two exposures, but that proved to be harder than expected as you can see below. I am not sure a grad ND would have worked here either, but it would have been better than mismatched clouds.

http://www.mystique.com/gallery/albums/album35/mirror_lake_001.jpg



Apr 25, 2005 at 04:39 PM
Ben Horne
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p.1 #2 · p.1 #2 · Polarizer Style


Get a traditional screw in polarizer. Here's why...... they work with hoods! If you get the cokin one, you give up the ability to use your hoods. Personally, I'd skip the cokin system. Just bracket your shots and digitally mask one over the other in photoshop. It's a lot easier, and it's free! I've gone through the cokin system, and the Singh Ray filters.... but sold them all.


Apr 25, 2005 at 05:05 PM
Jeff Donald
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p.1 #3 · p.1 #3 · Polarizer Style


I doubt a polarizer would have made much difference in the clouds because the dynamic range of the scene is the real issue. That picture would be easy to fix in PS if you shot Raw. The burned out highlights of the clouds could be salvaged and blended to match the reflections in the water. A graduated ND would work, but the rock races would have been darkened also, thus requiring more PS work.


Apr 25, 2005 at 05:12 PM
moondigger
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p.1 #4 · p.1 #4 · Polarizer Style


You can blend two exposures, as long as the camera was tripod mounted and the exposures were taken in relatively quick succession. As long as the darker exposure doesn't have burned-out clouds, you should be able to make a pleasing photo. Post the two images you used for this photo and maybe somebody will take a stab at it.


Apr 25, 2005 at 05:16 PM
Jeff Donald
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p.1 #5 · p.1 #5 · Polarizer Style


This is not meant to turn in to a debate about the merits of shooting Raw vs. Jpeg.

If you shoot Raw you don't even need two exposures. Process the same Raw file, in the raw convertor of your choice, twice. One image is processed for highlights, preserving detail the clouds, and the other is processed normal to give detail in the foreground. By using just one image you don't have to worry about movement from wind, subject etc.



Apr 25, 2005 at 05:22 PM
moondigger
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p.1 #6 · p.1 #6 · Polarizer Style


Jeff, while that might work when the dynamic range of the scene is only a little beyond what a single exposure can handle, it won't work when the dynamic range is really out of control. I'd still recommend shooting RAW for digital blending purposes, but it doesn't hurt to get two exposures.


Apr 25, 2005 at 05:29 PM
Jeff Donald
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p.1 #7 · p.1 #7 · Polarizer Style


One image will work if the highlights are over exposed by 2 stops or less.


Apr 25, 2005 at 05:41 PM
moondigger
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p.1 #8 · p.1 #8 · Polarizer Style


When you say "if the highlights ae overexposed by 2 stops or less," what do you mean by that? Are you saying if the highlights are two stops off the right side of the histogram you can still retain detail? Two stops off the right side is just blown -- no useful information in my experience, no matter how you process the RAW file. Or am I misunderstanding what you're saying?


Apr 25, 2005 at 05:51 PM
 

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nutek
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p.1 #9 · p.1 #9 · Polarizer Style


If you're developing 2 versions off the same RAW file, one exposed for the highlights and one for the shadows, then you will be inherently losing quality, since one of the versions will be noisier (and whatnot) than the other.

If you want to maintain absolute quality in both highlights and shadows, then you should take double exposures, with each exposure correctly exposed for the highlight and shadow respectively.

Unless the scene dictates that only a single-exposure must be captured (e.g. fast moving clouds, long exposures, people moving, etc), I would prefer double bracketted exposures.



Apr 25, 2005 at 07:08 PM
moondigger
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p.1 #10 · p.1 #10 · Polarizer Style


nutek wrote:
Unless the scene dictates that only a single-exposure must be captured (e.g. fast moving clouds, long exposures, people moving, etc), I would prefer double bracketted exposures.


That's what I'm getting at, though I'm still interested in Jeff's comment about highlights being two stops over and still useful. I'm still learning, especially when it comes to post-processing... and if there's a way to get useful information out of a file that's two stops overexposed, I'd like to know how.



Apr 25, 2005 at 07:18 PM
Jeff Donald
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p.1 #11 · p.1 #11 · Polarizer Style


Here are examples of blending images together. The wing of the Osprey appears to be blown out and the histogram bares it out.


Apr 25, 2005 at 10:43 PM
Jeff Donald
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p.1 #12 · p.1 #12 · Polarizer Style


Here is the second image, converted in ACR and the histogram shows a two stop change in exposure. Notice the change in exposure and detail in the wing.


Apr 25, 2005 at 10:44 PM
Jeff Donald
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p.1 #13 · p.1 #13 · Polarizer Style


Here is the blended image. Most of the detail has been restored to the wing. No other part of the image was changed so noise is not an issue. This took less than 5 minutes to accomplish and more work could have been done to improve the image. This was just meant to illustrate my 2 stop reference in my above post.

Double bracketed shots are impossible with flight shots. Noise is not an issue when darkening highlights.



Apr 25, 2005 at 10:44 PM
moondigger
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p.1 #14 · p.1 #14 · Polarizer Style


Jeff, that's good... but is there some special step that has to be taken during conversion? When I convert from RAW in DPP I don't see anything quite so dramatic in terms of highlight detail recovery.


Apr 25, 2005 at 11:14 PM
Jeff Donald
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p.1 #15 · p.1 #15 · Polarizer Style


I guess it's just PS, ACR, and Thomas Knoll knowing how to manipulate the pixels. I did two conversions in ACR and moved the dark image (-2.00 exposure change) on top of the light image. I then added a Layer Mask and used the Brush tool to "paint" in the dark version. I use an opacity of about 20% and brush over the spot until the desired effect is achieved.

The full resolution version has much more detail than the web version above.



Apr 25, 2005 at 11:25 PM
nutek
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p.1 #16 · p.1 #16 · Polarizer Style


Very nice!

Your example however does show only a tinny portion that has been blown out. If any more of the picture (as in % of the histogram) had been blown out, it would have been more difficult to recover it then, since there is a limit to even how much RAW can recover from the overexposure by. But it is an excellent tutorial and demonstration, thanks!



Apr 25, 2005 at 11:47 PM







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