Correct use of polarizing filter

[tbs]

After all these years (25?) of shooting slides (mostly Kodachrome) I find that I

am still puzzled by what seems like a very elementary subject: how to use a

polarizing filter.

 

I just got back three rolls of slides of a recent trip, mostly of Grand Canyon

and Red Rock Canyon (near Las Vegas), some of which were shot with polarizer,

some without. Some of the shots using polarizer look good, colors slightly

enhanced, improved shadow detail, reduced glare from bright rocks. Some other

of the shots with polarizer look like I was photographing during a solar eclipse

with a piece of clear blue plastic over the lens. This has happened other

times, and as I get pickier about the results, I find myself more and more

frustrated when this happens.

 

The lenses were all recent Nikon AF lenses, with a B+W PL-C (circular) filter,

the ISO was set correctly (the camera does it automatically, but I always check

anyway), and I made sure to have the sun behind me or to the side, never right

in front of me. I don't think the camera's meter has any problems.

 

Any hints?

[w.smith]

Hi Thomas,

 

polarizers' effect is greatest, if turned for max effectiveness of course, with the sun at

right angles to the lens axis. Vice versa the polarization effects - color saturation,

reflection control - is least with the sun behind you. But the 'Neutral Density' effect is still

there. It could be that is what you have captured.

[mark u]

Many polarising filters have an index mark (white bar) on the ring. If you turn the ring so the index is pointing toward the sun, the polarising effect is maximised for the direction in which you are shooting. Turn the ring 90 degrees, and the effect is minimised. The need to do this is why the filter rotates even when tightened onto the lens filter threads.

[plasma181]

There is another complication. Do you have a linear polarizer or a circular polarizer? A circular has a piece of glass that scrambles the light again after the polarization process. This will work on any camera. Some new cameras, both film and digital, can not take the older linear polarizers because it confuses the light meter giving you bad exposure.

[stephen hazelton]

It might help to post some sample pictures.

 

I just watch through the viewfinder as I rotate, see what looks good. A lot of times, the maximum polarization angle is not the prettiest.

 

I remember Bob Shell writing about how a british writer criticized him for overusing a polarizer on shots he hadn't used a polarizer on- shot in dry mountain air- perhaps some food for thought if shooting in the Grand Canyon.

[tbs]

I'm getting a scanner in about two weeks. Until then, no samples, alas. (My wife promised me a Nikon CoolScan 5000ED for Christmas, to scan all the Kodachromes I've been taking since I was 11 years old.)

[profhlynnjones]

Cameras in which the meter cell is behind a semitransparent mirror will sometimes transmit light and sometimes not, depending on the angle of the polarized light. This happens with a linear pola screen, if you will use the circular polarizer your problem will be solved.

 

Lynn

[david_henderson]

He has said that he's using a circular polariser. If he doesn't like the effect its creating then its the way he's using it and maybe the decision to use it at all that's at fault, not the type of polariser.

 

Its certainly very possible to over-polarise in the desert SW, and I expect may of us have done it and learned from it. It is especially prone to happen in conditions of clear blue skies which are already strongly coloured-and this also seems to happen at altitude.

 

Fortunately the cure is relatively simple. The degree of polarisation is variable by turning the ring and the learning process involves looking ttl at the scene with and without polariser, and setting varying degrees of polarisation, before settling on an approach. Indeed ideally you'll settle for a degree of polarisation just a little less than you want to see on the slide since the effect of filters tends to be somewhat greater than what you think you see through the lens. It is not correct to habitually adjust the polariser so that the effect through the lens is always maximised. It isn't correct to use a polariser whenever it has an effect.

 

So vary the degree, and learn to look carefully ttl, and you'll get there.

[david_fields1]

Shoot with a manual focus. Get two polarizers, a good multi-coated for your lens, and a second-hand one to carry in your hand to preview prospective scenes while leaving your camera in the bag. Look around at or near 90 degrees to the sun through your "hand-held" and if something looks like a potentially good photo, bring out the camera and shoot. If not, come back at a different time of day and see what you get. And of course as allways, underexpose because it's slide film.

Kodachrome 64 "polarized" can give GREAT royal blue skies if the sky to begin with is, sort of frosty, no haze, with lots of cumulus'.

This is a great film though much derided by chronic E-6'rs

[tbs]

Thank you all for your responses. I have been using a circular polarizer, as I said earlier. I know that turning the ring can give different degrees of polarization; I've seen that looking through the lens.

 

I was using it in Red Rock Canyon mainly because it was a bright morning and was trying to knock out some of the glare reflecting from some of the whiter rocks. What I saw sometimes as I turned the ring while looking through the viewfinder was the sky dark blue, and the ground and rocks slightly enhanced but their proper colors. When I turned the ring farther around, the sky got lighter, but the ground and rocks took on a slight bluish tint. Since the sky (unfiltered) was already fairly blue, I tried this position a few times, but the results, as I've stated earlier, weren't very satisfying.

 

And, although I know nearly everyone recommends underexposing slide film such as Kodachrome 64, I usually don't do that any more. I used to do that a lot, but I find now that that produces a slightly dim result (my wife said it looked like an eclipse was underway in some of the shots I did this with.) I now shoot K64 right at stated value most of the time, and usually it looks great. The only problems came when using the polarizer, which is what started this thread.