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Polarizers: the most useful and most costly filter (esp. for Reflections)

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ConsAreLiars Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Aug-10-05 12:57 AM
Original message
Polarizers: the most useful and most costly filter (esp. for Reflections)
Most useful, because it controls reflections, and light does have a reflect off of almost everything, making some of what you see/photograph "too bright" and often washing out the color that they eye can interpret but the film captures only as white. Often used to reduce the reflectivity range of a subject, like the sky or wet stuff, it can also be used to enhance or diminish the reflections from glass or water, and thus control the strengths of what is reflected versus seeing through the reflections.

The "costly" side of it is not only the initial price (if you get a new one for UNDER $50 you are getting ripped off), but the fact that they cost 2-3 f-stops of light hitting the film/sensor. That means that if you are shooting at 1/60th second wide open, you will need a tripod and be shooting at 1/15 or 1/8th second, or that if you are using ISO 100 film you will need to swap it for ISO 400 and suffer the losses in quality that result.

There's a basic description of how these filters work and their most common uses at:
http://www.luminous-landscape.com/tutorials/polarizers.shtml

For me the greatest value is that in a whole lot of landscapes the color gets washed out by small reflections of skylight that bounce off leaves or rocks or whatever unless a polarizer is used. Making the sky bluer, etc. is pretty secondary to this feature.

Following is an image where I used the polarizer to get just a slight reflection of the bright waterfall and "see through" the water to the rocks beneath the the surface. Without it the film would have shown a bright reflection of the falls in the pool and a dark surface elsewhere, with very little of the rocks visible.

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Immad2 Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Aug-10-05 09:22 AM
Response to Original message
1. Ohhh Boy! That's a beauty! Polarizers huh? I'm going to have to start
saving.Thanks
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regnaD kciN Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Aug-10-05 11:03 AM
Response to Original message
2. The other big problem with polarizers...
...is that you generally need an SLR (film or digital). Most compact digicams (even a high-end one like my Nikon 5700) won't take filters. :-(

I'd also like the opportunity to attach a graduated-density filter for overly-bright skies.

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Touchdown Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Aug-10-05 02:05 PM
Response to Reply #2
4. Yeah, they do. I've got an 8700 with a set of 4.
filters...only use the UV for myself. The camera already has a serious problem with ISO 400 and grain.

http://www.amazon.com/exec/obidos/tg/detail/-/B0002AHQS2/104-0652937-0032767?%5Fencoding=UTF8&v=glance

You need this as well...

http://www.amazon.com/exec/obidos/tg/detail/-/B00023JL96/104-0652937-0032767?%5Fencoding=UTF8&v=glance

It's metal, so don't let the pic fool you.
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regnaD kciN Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Aug-11-05 01:35 AM
Response to Reply #4
7. Thanks!
I'll probably be picking up one of these as soon as I have the cash.

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Touchdown Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Aug-10-05 01:57 PM
Response to Original message
3. The polarizer changed the color.
Polarizers sometimes do. Unless this shot was taken on Seti Alpha 7 from Star Trek, I can't see how water can be lavender, unless you color balanced the shot to make it appear that way.

Not to argue with you, as polarizers have their uses, but I see it as too much of a fallback position, when a simple composition change, a UV filter for glare(which only knocks it down 1 stop, if any), or re-orientation of the shot from another angle relative to the Sun could solve much of the problems that polarizers supposedly solve. Never been a fan of 'em.
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ConsAreLiars Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Aug-11-05 12:10 AM
Response to Reply #3
5. No, the scanner shifted the color - repost of more accurate image
(I have both the slide and a print made a while back for comparison.) I didn't bother correcting the color since I just meant the photo to illustrate one capability of the polarizer. I swapped in a truer version by substituting files on the server but it didn't load for me, so I deleted the original and am posting the color corrected version below.

It would have helped if I had made a version with the polarizer off, and also one where it was used to maximize reflections, but we've all seen images showing light reflecting off water surfaces. At that falls, perched in that spot, there were a wide range of images possible with a polarizer that would not have been possible otherwise.

As for how polarizers shift color (not the way that scan did), typically, at least in scenics, they add "sky blue" to the image or subtract it, as the reflective surfaces are usually reflecting the color of the sky. Often, this washes out the color that the film records, since unlike the eye-brain film is a just a dumb recording device that does no image processing other that implied in sensitivity curves.

I agree that the best filter is none, whenever getting the image you want is possible that way, and a UV filter is the top contender for the best-buy must-have category. It is a good cheap lens protector in the first place, and UV light will wash out landscapes in a way that you won't recognize without trying it. And it costs nothing, zero, zip, in terms of light transmission.

Revised photo:



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Touchdown Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Aug-11-05 09:09 AM
Response to Reply #5
8. OK, Mea Culpa.
I was kind of out of my mind when I criticized your shot harshly like that. I'd just gotten off (and pissed off) of one of those weekly "Beat up on meat eaters, because they're constipated and going to die of heart disease" threads over in GD. Sorry about that.:dunce:

It is a beautiful shot BTW. Your new scan cleans the color balance up a lot.
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ConsAreLiars Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Aug-11-05 11:13 PM
Response to Reply #8
9. No sweat
Your point about UV filters was helpful, and I didn't see the comments about the color balance as unwarranted or critical. I should have taken the few minutes to fix it before posting,

Anyway, everyone knows that meat-eaters get cranky when constipated. :evilgrin:

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Touchdown Donating Member (1000+ posts) Send PM | Profile | Ignore Fri Aug-12-05 10:06 AM
Response to Reply #9
10. Don't start with me.
Edited on Fri Aug-12-05 10:11 AM by Touchdown
Twice a day for 20 years if you want to go there. I call 'em my daily doubles.;)

The idea that I'm a callous brute for satanically cooking the lovely, emotionally sensitive, Disney beautiful creatures such as this one...



...is just too much looniness for me to ignore.
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F.Gordon Donating Member (1000+ posts) Send PM | Profile | Ignore Thu Aug-11-05 12:31 AM
Response to Reply #3
6. Troublemaker
:hi:

I use a Polarizer and ND filter quite a bit. I'll freely admit that I only have a pre-school level understanding of both. I've discovered that Photography is not like "riding a bike". You do forget. (at least I have)

I've been learning and taking test shots with both. Using a dual layer Polarizer or a ND filter I've used 1 second exposures on daylight shots. (primarily Water) A cloud or two can help out and shade is always helpful... but still.... 1 second exposures? And no over-exposure. Granted, running up at F/29, but still....

A harsh reality that I've recently had slap me in the face is that a good set of filters would run me over $1,000. Aint going there. I'll just learn how to better use PSP9.

So..... I respectfully disagree. I've personal seen the benefits of using a Polarizer and I've seen a ton of A-B comparisons on the web.

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