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Polarizing Filter for a Pocket Camera

Face it. As far as I know there is no such thing as a polarizing filter for a pocket camera. Most filters can be simulated by the cameras settings or later by adding effects with photoshop or a similar program.

Polarizing filters, on the other hand just can’t be digitally copied. They actually filter out light waves that are vibrating in certain directions and end up taking a completely different image without much of the reflected light that enters the lens without one. They are essential if you want to take pictures with a deep blue sky and vibrant colors.

I really wanted a polarizing filter for a pocket camera, so I went out and bought a cheap pair of sunglasses with one of those “polarized lens” stickers on it. I then popped one of the lenses out of the frame so I had a piece of polarized plastic to work with. A simple rubber band worked to asphix the “filter” to my pocket camera, and wah lah! I have a polarizing filter for my pocket camera for close to nothing spent and am ready to create compositions with a deep blue sky in them.

The photo above is a blue sky taken without a polarizing filter. It’s ok, but the sky is a bit pale, and has a greenish smoggy tint. Compare it with this one that I took with my makeshift polarizing filter for a pocket camera. You’ll see the blue sky is much deeper, and the white clouds are whiter as well.

I’ve found the rubber band takes a bit too much time to fiddle with, and have learned to simply hold the sunglass lens in front of my camera while I shoot. It takes some juggling, but but I’m pleased with the results.

Shutter Speed, Aperture and ISO

Digital cameras are based on a sensor that reacts to the light reflecting off the subject of the photo you are taking. A certain amount of light is required in order to get a good shot, and that optimum amount of light is basically the same in any situation.

The three things we have to play with to adjust the amount of light are shutter speed, aperture and ISO.

Shutter speed and aperture are closely related. If you increase the aperture (lower F-Stop number) more light gets to the sensor, so the shutter speed has to be increased to adjust the amount of light. Conversely, if you choose a small aperture (bit F-Stop number) then the shutter will have to stay open longer to let in more light. Think of filling a bathtub. If you open the tap all the way (aperture), the tub will fill in less time, and you will turn the water off sooner (shutter speed).

In order to get a good exposure, you need the right combination os aperture and shutter speed. Most cameras have settings where you can adjust one and the camera will automatically adjust the other to compensate and give you a great shot every time. If you have a more professional camera, you may be able to override this feature and choose both manually, and alas, some point and shoot models give you almost no freedom. I have one model that has no aperture settings at all.

In terms of exposure, a narrow aperture/slow shutter speed will give you the same result as a wide aperture/fast shutter speed combination, but varying the aperture also affects the depth of field (DoF) or how much of your subjects background will be in focus. If you are trying to achive a blurry background like in our cherry blossom shot above, you will want a narrow depth of field which can be achieved by choosing a wide aperture setting (low F-stop number), or if you can’t control that, and fast shutter speed, which will force the camera to change the settings to increase aperture.

ISO used to indicate the sensitivity of the film you were using. A high ISO film was more sensitive, and needed less light. Now that most of us are using digital cameras, the ISO setting is actually just a simulation. Increasing the ISO number will cause the camera to have a higher shutter speed which may result in a small depth of field, but use it in moderation, as you may see more digital noise with a highter ISO (that awful ‘grainy’ effect)

Once again, if you want to achive that ellusive blurry background:

Thanks to Elizabeth Laurel for the great shot of last spring’s cherry blossoms!

Polarizing Filters and UV Filters

There are several different kinds of lens filters serious photographers use regularly. If you have an SLR camera, you will be able to buy filters that screw onto the front of the lens. Two of the most basic filters are polarizing filters and UV filters.

UV filters

A UV filter is the most common type of lens filter. It serves to partially remove the incoming ultraviolet light. Ultraviolet light isn’t a problem at sea level but as you gain altitude, UV levels increase. The blue color you see in the distance in landscape photos is generally produced by ultra violet light. Some film types are UV sensitive, and will result in a bluish tint if used at high altitude. A UV filter will solve this problem, but I understand that most digital sensors are not sensitive to ultraviolet light, so a UV filter isn’t necessary unless you are using film.

A UV filter on a digital camera probably does very little except protect the front of the lens, and perhaps help to reduce haze or smog. In most cases if you have a digital camera you won’t care about ultraviolet light, so it would be just as effective to use a plain filter of clear optical glass to avoid scratching your lens.

Polarizing filters

Polarizing filters are an entirely different type of filter. We all know that light is a series of waves. Normal light has waves that undulate in all directions. A polarizing filter is like a net that only allows light waves going in a particular direction to get through. Light reflected from certain surfaces is also polarised in a particular direction, including some of the light reflected from the sky. A polarizing filter can be used to prevent this light from entering the lens, thus reducing glare and darkening the colour of the sky.

A polarizing filter is generally used to produce deep, rich blue skies. Most filters are attached to the lens in a fixed position but a polarizing filter is rotated by the photographer. As the filter rotates, the polarizing effect increases and then decreases – looking through the lens, you simply turn the filter until you like the effect. With a polarizing filter, blue skies look great and even better when there are some white fluffy clouds to provide contrast. Be careful, though if you are using a really wide angle lens (24mm or wider)The polarizing effect may not stretch across the image frame and you could end up with an unattractive two tone sky.

A polarizing filter can be used to increase color saturation in many different areas. Green foliage and even red roof tiles can look extremely vibrant. Because the color saturation is increased, your shadows may turn out much darker than you had planned, and hide or darken some of the subject, so watch out for that.