Starting September 2011, Carl Zeiss will be offering four new diameters for UV and POL filters (circular): 52 mm, 55 mm, 62 mm and 77 mm. With these new sizes, the company is expanding its range of filters, which until now have only been available in diameters 58 mm, 67 mm, 72 mm and 82 mm. (press release). In this article, we discuss how POL filters can be used to create impressive visual effects. The photographs in this article were taken with a full-format DSLR camera with ZEISS Planar T* 1,4/50 and Distagon T* 2/28 ZE lenses.
POL (polarizing) filters help to remove unwanted reflections from smooth, non-metallic surfaces, e.g. water or glass, while at the same time improving color saturation and intensifying contrast. In nature and landscape photography, for example, the green rendering of foliage and grasses is enhanced by the filtering out of bothersome (blue) reflections of the sky by a POL filter. The sky itself appears a lush, vivid blue, and contours and individual clouds are better defined through the use of a POL filter. POL filters are also ideal for photographing reflecting water surfaces.
Only for sunlight
The POL filter is attached in front of the camera lens and is then rotated manually by the photographer until the desired filter effect is achieved (for example until the reflectionsdisappear in the viewfinder or on the display). POL filters are penetrable for specific directions of oscillation of light, and absorb other directions of oscillation. Therefore, this makes their use in outdoors photography practical only when the sun is shining. In cloudy weather, the filters have virtually no effect, owing to the almost complete lack of polarized light present. The increase in color saturation is dependent on the angle of incidence of the sun and corresponding rotation setting of the POL filter. The effect is greatest when the sun is at an angle of approximately 60 to 90 degrees horizontal to the view direction.
The difference in color saturation achieved by a POL filter is particularly evident in these photographs of the fender of a classic truck. Without a POL filter, the sun is reflected in the black-painted bumper and appears light grey to white. In contrast, with a POL filter, the actual reflections are removed and the original color - black - appears intensely. The effect is similarly apparent in matt-colored red. Without a POL filter, the sun’s powerful reflections produce a glaring cone of light. With the POL filter, however, the red color appears bold and vivid.
The conditions in this picture proved challenging for the photographer:
It can be seen in the black vehicle paintwork that some minor reflections remain, despite the use of a POL filter, since these occur at a different angle to the suppressed reflections in the optical axis, owing to the pronounced curvature of the headlamp and the hood. In the picture, the photographer selected the rotation angle in such a way so as to largely remove the strongest reflections, caused by the reflections of other vehicles.
A vivid blue sky
The following example illustrates the enhancing effect of a POL filter on a blue sky.
The supersonic passenger jet Concorde, which is no longer in service, is shown in these two photographs at the Automobile & Technology Museum in Sinsheim, Germany. The photographs clearly show the significant improvement in contrast between the clouds and blue sky as a result of using a POL filter. The shadow on the pillar in the right of the shot indicates that the sunlight is coming from the right, at a favorable angle of incidence of almost 90 degrees. With backlighting or in incident light, i.e., with the photographer’s back to the sun, the effect would disappear entirely.
Working with water
The following two photographs demonstrate the effect of using a POL filter on reflections on water.
By eliminating reflections on the water’s surface, the photographer is able to emphasize details of the lakebed. The green of aquatic plants is rendered in luscious, natural greens, whereas without a filter these would appear merely “grey in grey”.
However, the use of a filter is not always beneficial when working with reflections on water. In certain situations, reflections can produce an exciting image composition, for instance where trees or buildings are reflected in water, or like the pond reflection of a building in the picture below. Here, the intention of the photographer is what counts.
When to use a UV filter
Finally, a few points on the use of UV filters: these are used to block out ultraviolet light, yet they remain transparent and fully permeable to visible light. In certain situations where there is a high proportion of UV light (for example at high altitudes), the image contrast can be slightly increased and the sharpness enhanced by filtering out undesired wavelengths. As a result, colors appear more radiant. T* UV filters do not lengthen the exposure time, which makes them ideally suited for everyday use, particularly for protecting the front lens from dirt, dust and scratches, and even from slight damage if the lens is dropped.