I recently bought the 55mm f4 lens, and am considering a polarizer. However, when using a (circular)polarizer on my wide angle Nikon lenses, there often is a noticeable darkening toward the edges of the image (not to be confused with vignetting). It is an uneven density mostly visible where the sky is shown.

Can I expect this effect if I put a polarizer on my new lens as well? And are there superior quality polarizers available that minimize this effect?

Any info would be greatly appreciated.

-- Hillary Charles (hocusfocus@netrax.net), October 10, 2001

Answers

To add a bit to Bobby's excellent answer; one trick to use when one encounters this problem with uneven polarization is to not polarize the scene fully. Doing so will will reduce this affect but not totally eliminate it. With very wide lenses, the sky is usually quite blue just because the angle is wide enough to see to the darker, upper area of sky. So, the use of a polarizer is not essential. With my 45mm, I will sometimes use the polarizer but usually in verticals and usually partially polarized. I don't even use a polarizer on my 20mm Takumar on my KX. Strangly enough, I have seen many shots published that had obvious uneven polarization.

-- Steve Rasmussen (srasmuss@flash.net), October 11, 2001.

Hillary, your problem may not be due to poor quality polarizers. The degree of polarization in a sky depends on the angle of the sun to a particular portion of sky. Since extreme wide angle lenses cover a very wide expanse of sky, not all of the sky will be polarized the same. In the photograph, one side or the other of the sky image will be darker, and gradually get lighter across the image as the degree of polarization is lessened.

I have noticed this effect quite often when using 20mm or wider lenses on 35mm cameras. With lenses in the 14mm to 15mm range it is virtually unavoidable, which may be why most of these extreme wide angle lenses don't take polarizers at all. It is not so noticable with 28mm lenses though, which your 55mm 6X7 lens is about equal to, in angle of view, so you may not notice it much. I tend to take a lot of vertical photographs, even scenics. This helps since the width of sky is a lot less than if taking a horizontal shot. Of course not every shot fits the vertical frame, and some people prefer the horizontal format best for scenics.

You can usually see the effect in the viewfinder, although it is far more noticable in the finished photograph. Try pivoting the camera left and right as you adjust the polarizing filter and see if the effect is lessened or magnified as you change your point of view to the subject. You will find that some shots just won't work no matter what you do. This is just one of the problems scenic photographers have to deal with. But, you will find there are times when everything works perfectly, and it is times like these that keep us photographing. Bob.

-- Bobby Mahaffey (mahajen@prodigy.net), October 11, 2001.

I knew I came to the right place! Thank you for your answers--they make perfect sense. Somehow, I got it into my head that it was some optical artifact of the wide angle/polarizer combination. The fact that a wide angle would take into view enough of the sky not affected by the filter is obvious to me now.

I love to maximize saturation, but will have to use discretion. Better no polarization than an ugly uneven sky. Guess I gotta just keep the 67 loaded with Velvia in either case.

Thanks again!

-- Hillary Charles (hocusfocus@netrax.net), October 11, 2001.