Both hard and soft edged filters come in several strengths. The popular ones being one and two stop. A two stop filter is needed if the sun is front of you. Otherwise you can use a one stop filter.

Grad ND filters are available ¡ri circular or rectangular shape. The rectangular type Grad ND filters can be moved up or down in a holder so that the transition can be moved up or down to align with the horizon of the scene you are photographing. (The most popular holders are made by a company called Cokin). This flexibility is not available in a circular Grad ND filter as the transition is always fixed at the middle - exactly where you should not keep the horizon for a good composition! Hence do not buy such filters: Also filters mounted in holders can

O Without Graduated ND Filter

be rotated 90° so that they can be used in portrait (vertical) and landscape (horizontal) orientations.

Polarizing Filters: fhese are very popular with landscape photographers. In fact the saying is that if a landscape photographer has to carry just one filter, then it should be the polarizing filter. Compared to all other filters polarizing filters are constructed in a different way. There is a circular metal ring like in any other filter that screws on to the lens, but the glass part of the filter is not fixed onto this. It is fixed in ar. inner ring which rotates within the outer ring.

So, how does a polarizing filter work and how does it help landscape photographers? A ighl ■"clleclcd IroT nor metall c surfaces get polarized, thai is it vibrates only in one plane. The polarizing filter has optical characteristics such that it will allow passage of light polarized only in one plane. You can change this plane by rotating the inner ring and thus choose a position such that the plane of reflected light is at right angles to the plane of passage through the filter.

O With Graduated ND Filter

This blocks the reflected light from reaching the sensor thus eliminating reflections. This operation is not as complicated as it sounds as you can see this effect very easily in the viewfinder of a D-SLR as you rotate the polarizer. Polarizing filters generally reduce light by about 1.5 stops and can also be used like an ordinary neutral density filter too.

For a landscape photographer, the most important use of a polarizing filter is that it darkens the skies dramatically under certain conditions. On a clear day a lot of light is polarized due to reflections from particles in the air By using the polarizer and pointing the camera in the right direction, you can block the polarized light from the sky and get a very deep blue sky. Note that this effect is not possible on cloudy days where the light is scattered in all directions making the polarizing Slier ineffective.

So, how do you find out the exact area where the effect (called the polarized band) is at its maximum? This is rather simple. First see the diagram which indicates where the polarizing band is. It is at right angles to the sun. Make

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a right angle between your fore-linger and thumb and point your thumb at the sun Now, if you move your forefinger by the movement of your wrist, the forefinger will make an arc which indicates the polarized band. You can see that when sun is low the band will be upwards and when the sun is right above, the band will be close to the horizon.

If you are photographing a scene in sunny conditions, foliage can reflect light and reduce contrast. Likewise water can reflect light. In these cases a simple twist of the polarizing filter can eliminate the problem very effectively

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