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Old Mar 21, 2005, 12:45 PM   #1
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A newbie question for someone new to filters.

If I purchase a circular polarizer filter for my lens would I also need a UV filter or can the circular polarizer filter be set that it has no effect in times when it would not be needed (keep it on to protect the lens)?

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Old Mar 21, 2005, 2:12 PM   #2
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Any piece of glass can filter UV...

However a polarizer is not very efficient @ transmitting light and will cut several stops even in the neutral position

It's OK as long as you don't need the shutter speed, but in most case it will slow down the camera quite a bit especially especially indoor if you don't have a fast lens in the 1st place...
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Old Mar 21, 2005, 2:16 PM   #3
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Although you could leave a circular polarizer on you camera all the time, it is probably not a good idea. Even when the polarizer is rotated for minimum effect, it will still reduce the light "seen" by the lens. This reduction is 1-2 f-stops. In automatic mode, this will result in slower shutter speeds or larger aperture (with resultant recuction in depth-of-field). It is the same as using an ND2 or ND4 neutral density filter.

Another reason for not leaving the polarizer on the camera is the cost of the filter and the potential for physical damage. The front element of the camera lens needs to be protected but it is much cheaper to use a UV filter for that purpose.

Yet another reason is possible vignetting. The frame of a polarizing filter is about twice as thick as other filters. This is because it has two rings. One screws into the filter mount on the lens and the second is the one you rotate to adjust the polarizing effect. This double ring might cause problems with extreme wide angle shots.

It's up to you. I've given some cons. Maybe someone else has some pros. Good luck and show us some great shots.

Cal Rasmussen
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Old Mar 21, 2005, 2:31 PM   #4
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I agree with Cal, it's a costly lense protector to use a Cir Polarizer. Also, if you get a multi-coated one it should help cut down on amount of light lost. You still don't want to leave it on the camera. Now, having said that - it brings me to my next point - multicoated circular polarizers are a PAIN IN THE BUT to clean - a regular UV filter is easy to clean.
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Old Mar 31, 2005, 5:44 PM   #5
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agiaccio wrote:
Quote:
A newbie question for someone new to filters.
Same topic, different problem:

I got a circularpolarizer for my Exlim P600 last week, in hopes of getting some nice cloud/sky color/detail/contrast. No joy. Rotate it as I might, I see no earthly difference in the images. Does anyone else have this problem? What am I doing wrong?

TIA

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Old Mar 31, 2005, 7:02 PM   #6
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F2Guy It has been my experience that if you put the filter on so that it the polarization is horizontal you get about the best you can. Filters often have a mark so that when it is straight up it is giving the best polarization in most cases.

If you don't have a mark you can make your own with a pair of polarized sunglasses. Make sure they are perfectly level and rotate the filter in front of them until it goes black. Mess a little to make sure you are centering on the dark and make a mark on the side of the filter. When the two line up to give you black you have the filter at exactly the angle you do not want it for photography. So if you make a mark on the side and shoot with that mark straight up you will get at least 90% of the effect.

I always wear polarized glasses so I tilt my head a little one way or the other to see if I can get a little more effect. I usually can't, but if I do I just match the mark to the slight angle I'm holding my head.

The problem is that LCDs don't give enough view to make critical corrections – especially in bright sunlight. You could remove the filter and view the scene through it. Observe where the mark is and put it there after you replace it on the camera. But you won't do much better than putting the mark straight up.

Some parts of the sky are polarized more than others. The effect is dramatic when you get a highly polarized blue sky with white clouds. Are you taking the same shot both with and without the polarizer?

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Old Mar 31, 2005, 10:47 PM   #7
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Slipe, the problem with your method is that even if you mark the orientation of least polarizing effect, you will still have 1-2 f-stops of light loss due to the dark color of the filter. Also, the orientation of minimal effect will vary with your angle to the sun.

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