Polarizing filter help

[Christina]

I shot some images of a cathedral reflected in the windows of a building across the street on my lunch break yesterday. I was using a Tamron 17-50mm lens with a polarizing filter... which from what I understand, is supposed to reduce glare. However I clearly did something wrong, as my images all came out looking like this:

http://montemama.zenfolio.com/img/v2/p916266513-3.jpg

I've really been enjoying POTN and have learned a lot by lurking over the past couple months. :) I'm hoping someone might be offer some tips about how to correctly use a polarizing filter... I seem to have the wrong way down already. :o

[timnosenzo]

Did you try twisting the filter while looking through the viewfinder? You should notice a difference in the effect when you do.

[rammy]

Where was the sun in relation to your target/shooting line? It should be at 90 degrees and you need to twist the end of the filter, as suggested, to see the effect.

[Christina]

Did you try twisting the filter while looking through the viewfinder? You should notice a difference in the effect when you do.

I didn't try that. But I will, thanks.

Where was the sun in relation to your target/shooting line? It should be at 90 degrees and you need to twist the end of the filter, as suggested, to see the effect.

I'm not sure how to figure where the 90 degrees comes from. Do I envision a line between the camera and the subject, and then the sun needs to be at a 90 degree angle from that line?

[rammy]

The easiest way to remember is that the sun should be to your left or right and the subject in front of you.

[WaltA]

I didn't try that. But I will, thanks.



I'm not sure how to figure where the 90 degrees comes from. Do I envision a line between the camera and the subject, and then the sun needs to be at a 90 degree angle from that line?



Check out the explanation in this article
http://www.great-landscape-photography.com/polarizing-filter.html

[Christina]

Thanks for the link. I think that makes sense - will have to give it a try on our next sunny day. They do happen in Pittsburgh a couple times a year.

[iamaelephant]

The angle of the sun is irrelevant with regards to window reflections. That 90 degree figure applies only to a polarizing effect in the sky.

[Christina]

The angle of the sun is irrelevant with regards to window reflections. That 90 degree figure applies only to a polarizing effect in the sky.
Oh. So... can I fix what happened above by turning the filter? Or is there something else I should do?

[Glenn NK]

One other thing to keep in mind about polarizers - they have little effect on metallic surfaces, and I believe this includes glass surfaces.

I've worn polarizing glasses and sunglasses for years, and the glare from the rear window of a car in front of me doesn't seem to be affected by the polarizing sunglasses.

OTH, the glare from objects like water and leaves will be greatly diminshed.

By rotating the filter slowly while looking through the viewfinder, the effect you are going to get should be visible.

[Mark1]

Just spin the filter while looking through the camera. You will see the effect change intensity. You can even hold the filter in front of you, and look at the monitor through it. Rotate is and you can see it change. You dont need a sunny day to take advantage if a CP. Just need reflections or glare.

[Mark1]

I've worn polarizing glasses and sunglasses for years, and the glare from the rear window of a car in front of me doesn't seem to be affected by the polarizing sunglasses.




Rotate your head (ear to sholder) You will see it change. My sunglasses are polarized as well. With the flurry of questions here. It is in the back of my mind. So I have been playing with them a bit while driving.

They reduce glare on glass. But they can almost eliminate reflections on glass.

[iamaelephant]

Oh. So... can I fix what happened above by turning the filter? Or is there something else I should do?

To a limited degree, yes. I would advise taking your CPL out on a nice day and experimenting to find out what is possible.

[DStanic]

If you want to see the effects of a CPL filter, put some uncovered boiling water on the stove and turn on the light above the oven. Look at it through the viewfinder and turn the CPL and you should be able to see the change in the reflection. At least I noticed it when I did it before.

[Mark1]

Just noticed in the OP..... there is no glare to reduce.... those are reflections. But still a CP will help.

[Christina]

Just noticed in the OP..... there is no glare to reduce.... those are reflections. But still a CP will help.

I'm still confused. :o I also took some shots with other lenses without the filter (85mm and a 100-300mm) and none of them have that distorted look. Is it because I was at a different angle with those lenses?

Here's one with an unfiltered 85mm.
http://montemama.zenfolio.com/img/v2/p312168984-3.jpg

And one from a similar angle as the 85mm shot above with the filtered wide-angle again. Not as extreme here as in the 1st on in my OP.
http://montemama.zenfolio.com/img/v2/p209711953-3.jpg

[steven]

I'm not clear what distortion you are referring to.
Can you elaborate on what you mean by distortion?

Thanks
steve

[Christina]

I'm not clear what distortion you are referring to.
Can you elaborate on what you mean by distortion?



I'm sorry - I don't know how to describe it. What I'm referring to is most easily seen in the picture in post #1, where the reflection of the blue sky in the windows has a distorted, rippled effect, instead of a crisp, clear, smooth blue as in the first picture of post 16. Hope that makes sense...

[qtaran111]

Yep, sometimes you get those lines (looks like a sort of rainbow grid) on certain building or aeroplane windows when using a polarizer due to cross polarisation.

See here (http://www.ephotozine.com/article/Cross-polarisation) and here (http://www.ephotozine.com/article/Polariser-guide)

[Mark1]

You may need to re-state your question.

But here are a few answers at random.

You say "glare" but are asking about reflections. Polarizing filters are to help reduce reflections. So why are you taking pictures of reflections as a subject, but useing a polarizer?

If you are asking about why the reflections are full of waves....it is because glass is not really flat. The farther the object is from the glass the more apparent this is. Example. If you put a model, leaning agenst the window you will not see much distortion, But try to take a shot of the distant horison in the reflection it will be all messed up. Our brains can adjust for this. This is why we dont overly notice it live. The same way our brain can adjust white ballence. White looks white in Flouresent, Tungsten, incandesent, and sunlight. Enen though our eyes are not sending that signal.

It can be as qtaran111 stated. The filter may be producing a Moray effect.

[Glenn NK]

Not only is glass not perfectly flat, but the different panes of glass (glazings) are often not perfectly parallel to each other - which in effect means that the "mirror" is not flat - this also results in distortion.