shooting portraits with CP Filter?

Hi, I know CP filter brings more cloudness in the picture.

Would there be any bad impact on picture quality while shooting portraits outdoors on sunny day with CP filter attached?

Anything in front of the lens is going to degrade image quality. Hell, the lens elements degrade image quality. I guess you're going to have to trade off the effect of the polarizer against the tiny loss in IQ from having anything extraneous on the lens.

Thanks Paul for your reply. So, it is better to remove CP Filter while shooting portraits.

sgogula wrote in post #5600625
Hi, I know CP filter brings more cloudness in the picture.

Would there be any bad impact on picture quality while shooting portraits outdoors on sunny day with CP filter attached?

A polarizing filter is used to darken a blue sky or to cut through reflections (in non-metallic surfaces). There MAY be a good reason to use a polarizing filter while shooting outdoor portraits, but it's likely the reason is either to enhance the colors of the background or to help remove reflections in the subject's eyeglasses.

Using a polarizing filter effectively cuts about two stops of light from coming through the lens, requiring you to use a slower shutter speed for a given aperture and ISO combination. Thus, you should consider the potential benefit of using the polarizing filter before choosing to do so.

DO NOT stack filters. If you use a UV filter for "protection", remove it before installing a polarizing (or any other) filter.

Any filter you use should be a high quality multicoated filter. You are simply asking for degradation of your image if you choose to use cheap (and especially non-coated or single-coated) filters.

I don't know as though I agree with Paul. How can a lens element "degrade" image quality? If not for the elements, the image isn't even possible as you see it.

My answer is... it depends on the filter. Not all CP filters are created equal. Cheap plastic filters will degrade image quality... but a high end glass filter that is multicoated may cause an ever so slight degradation in sharpness and such, but it isn't anything you can ever notice, even when pixel peeping. It may show up in an MTF chart but the benefits can far outweigh the risks. A CP not only helps with sky/clouds but it also filters out reflections from all surfaces that reflect that light... like water/glass, painted surfaces, leaves on trees... yes, that's right, leaves and blades of grass cast reflected light... and a CP filter can reduce that depending on the angle you shoot from the sun. The result is richer deep colors that are free of specularity. Best thing is to try with it on...look through the viewfinder while turning it, and see if it is making a difference. If it's not, it's ok to take it off.

forkball wrote in post #5601497
I don't know as though I agree with Paul. How can a lens element "degrade" image quality? If not for the elements, the image isn't even possible as you see it.

Yes, I was thinking that as I wrote it, but it is true to a degree - there is no such thing as a perfect optic (although a very tiny handful get vanishingly close, and you won't find them in an SLR lens). Of course, you have to have a lens on the camera, I suppose what I'm saying is that the less glass the light has to pass through the better, although with good quality glass (and, to bring it back on topic, good quality, multicoated filters) the loss in quality can be reduced to insignificant levels.

All that said, I'm only really whiling away a sleepless night with such thoughts, since I personally use zoom lenses most of the time, trading off quality for convenience.