Polarizing filter

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Moderator Emeritus
Mar 9, 2005
Home base-Kernville, CA
I've been doing some research and am looking at buying a polarizing filter.  From the research I understand it should be a quality one.  It would be for my Canon Rebel XT 18mm to 55mm lens.  Any suggestions?

Regarding my 100-400mm lens, it seems that I might not need a polarizing filter for that lens....or maybe I do. 

Thoughts.... ;D

You need to know the thread diameter on your lens before you buy one. The 18-55 lens has a 58 mm threads. The 100-400 has 77 mm threads.

The polarizing filter is an odd duck because it is the only physical filter that cannot be replicated in Photoshop.

I recommend that you don't bother to buy one for either lens. They have very limited uses, especially on the 100-400. The problem is you can't just put it on and leave it on like a UV filter. A polarizer reduces the incoming light by one half to one and a half stops. So you must carry it with you and when you need it then install it and then take it off after you are done. The hardest part is seeing a scene and actually thinking "I need the polarizer for this shot". I bought one three years ago and I think I have used it once since then.

If you do get one I wouldn't spend a whole lot of money on the first one. Then if you find out you do use it a lot get an expensive one. A cheap one would be $20 and an expensive one would be $100.

This is a typical reaction of photographers who think that if they buy more equipment then their photos will come out better. Nothing could be further from the truth. It is the photographer not the equipment that makes the difference.

The typical use for polarizers is when you are shooting a scene with a lot of water. The polarizer will reduce the reflections. However, I find it much better off to shoot with the sun behind me then I don't need a polarizer. Another use is shooting a scene with snow. Do you go skiing a lot and take your camera with you?

Having said all that, if you need a polarizer there is no substitute. If I ever need one I will have to go back to my RV and get it.
Tom:  The reason a polarizer doesn't do much for you is that you shoot with the sun to your back and you shoot BIF with a lot of movement.  If you shot landscapes more like I do, the polarizer is great.  It should be used primarily for the sun being at right angles to your shot as well as water reflections.  When shooting macro, it intensifies the colors also.  It is important to not over polarize an image, although it adds drama, because it can almost turn the sky black.


All that being said, If you do get one, make sure to get a CPL not a linear polarizer. The liner type do not play well with certain functions of a DSLR.
Ron - I know that a landscape shooter would use one more than I do. But my point is that Marsha is not exactly an advanced photographer and she would probably not get a lot of use out of one, especially on her 100-400. There is no harm in her getting a cheap one for her 18-55 and seeing if she uses it or not. If I want more intense colors on macro shots I will just turn up the saturation control. I just want to warn her that it is not something she will use very often so she shouldn't go buying a $100 one right off the bat.
Ron - I should also mention that I don't always shoot with the sun at my back. When shooting birds, yes I do, but not all time on other occasions. I teach beginners that they should start out shooting with the sun to their back. That gives them the best chance to have their photos come out as they expected. However once they have mastered the basics then changing the position of the sun is a natural. I feel beginners should walk before they run. Learn how to get their photos to come out proper and then they can try more experimental approaches.
I shoot a lot of landscape shots with my 18-55 lens so I was going to play with the polarized filter.  I found one this morning at Best Buys for about $25 or so.  I thought I'd play with it and see if I even liked the results.  I was waiting to read these responses before I bought it.

Steve, I've been reading about the difference between the CPL and a linear one.  I was going to get the CPL.

Thanks for the info.


Marsha, unlike other camera filters, a polarizing filter rotates freely and you have to rotate it manually to get different effects.
CPL = Circular polarizer

There are two types of polarizing filters generally available, linear and circular. With the exception of how they interact with some autofocus and metering mechanisms, they have exactly the same effect photographically. The metering and auto-focus sensors in certain cameras, including virtually all auto-focus SLRs, will not work properly with linear polarizers because the beam splitters used to split off the light for focusing and metering are polarization-dependent.

Polarizes come in two types:

Circular -- for all types of cameras: required for beam splitting metering systems commonly found in auto-focus SLR's and in most current TTL SLR's.

Linear -- for older metering systems.
Thanks for that explanation.

Haven't used (tried) a polarizing filter since my first film SLR almost 40 years ago. I had no clue what I was doing with it and, as a result, was disappointed with the results. Put it aside and never tried to use it again. Having worn prescription polaroid lenses for some years, I now have a little better understanding of what they can do, and might buy one to.play with. CPL it is.
The SC20 doesn't have filter thread but your Rebel will. You probably have the same 18-55 lens as Marsha so you would need one with 58mm threads. You look through the viewfinder and rotate one of the elements until you get the best effect.
I leave my CPL on all of the time and take it off only when needed, which is seldom.  The beauty of digital photography is the ease of adjusting for less light.  You can kick the ISO up, reduce shutter speed, or increase apeture.  Only in real low light is it of much benefit to remove the CPL.

A polarizer is great for rendering a better sky. 

I also disagree with purchasing an inexpensive one.  I have done so and been very disappointed. 
The cheap filter/expensive filter debate has raged for longer than I have been a photographer. Not once have I seen one photo posted from the expensive filter camp that proves their point. So until then I will continue to buy/use/recommend a cheap filter. No use in spending money just because of undocumented opinions. The polarizer I have was cheap and I did not notice any problems when using it.
Well Tom, I can't say that I have seen any of your work hurt by an inexpensive polarizer.  I do know that I have bought a couple that were terrible.  I subscribe to the theory of putting only good glass in the front of the camera.
Well George that would be the result of the facts I rarely use a polarizer and if I did and there was a problem the photo and the image would go into the trash. My best photographic trait is my supreme ability to use the delete button.
A polarizer filter is two pieces of glass that are so close together and so thin they appear to be only one piece of glass. You first thread the filter onto the lens until it is tight, but not too tight using the inner ring (the one closest to the camera body). Then look through your viewfinder at the scene you wish to record. Rotate the outer ring of the polarizer and watch the effect it has on the image you see. When you get the effect you want then push the shutter button.

If you have ever worn polarized sunglasses you probably noticed that the scene changes as you tip your head to the left or two the right. That is because polarized sunglasses and polarized filters work on light that is polarized such as reflected light.

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