12/01/11The use of filters in photography is very much an individual decision, with opposing opinions amongst many pro-photographers. This article outlines what we use at Light and Motion, and the reasons behind it.
UV filters. This is probably the source of most debate with filters, the question being whether or not they degrade image quality. There are quite a few photographers who would never consider using a UV filter, or a lens cap for that matter, and use the lens hood as the primary protection for their lenses. These photographers often don’t pay for their lenses either. We feel that a good multi-coated UV filter has no significant effect on image quality, helps prevent flare, and also offers reasonable lens protection. These aren’t cheap, so there is little point to invest in them for kit lenses. However, for more expensive lenses we feel they are justified. When used with a lens hood, and without a lens cap, the UV filter offers additional protection while the camera is always ready for that once in a lifetime shot.
Circular Polarising Filter. The CP filter tends to be overused, but there are instances in landscape photography when they are very useful. We utilize them to reduce reflections from water surfaces, particularly in waterfall images. CP filters can also improve saturation, but this effect can be overdone and is obvious. Ensure the CP filter is off the lens before taking panoramic images, as most software will have difficulty blending polarized images. The following image was taken with a CP filter, which not only reduced reflections but also allowed the shutter speed to be lengthened given a 2 stop reduction in light.
Neutral Density Filters. ND filters are available in varying densities, and we use 2 and 3 stop ND filters to prolong exposure times for certain images. There is a school of thought that suggests that one should wait for the right natural lighting to occur, but there are times when this is not possible or practical. For instance, on our recent 6 day Overland Trek in Tasmania, we rose at or before dawn each day, but by the time we walked to the many areas of photographic interest, it was often mid morning or later. On such a trip you can’t be at every place of photographic interest at dawn or dusk. In such instances, ND filters allow some control of the light.
Beware though that some ND filters can produce a colour cast. Generally the cast worsens with the filter density, and exposure duration. As with most things in life, you get what you pay for, so we feel it is better to start out with one or two quality filters that have minimal cast such as Lee or Singh-Ray, rather than purchase cheaper kits with many filters. The following 2 images were taken in less than ideal light, but the ND filters allowed the shutter speed to be prolonged to capture motion which would not have been possible otherwise.
3 stop ND filter, ISO50, f16, 1.6sec
3 stop ND filter, CP filter, ISO50, f20, 0.3 sec. This was taken in bright sunlight, and the 3 stop ND filter helped prevent the water becoming overexposed with a 0.3 sec shutter speed.
10 stop ND filter. Significant debate also exists over the use of this filter. There is no doubt that a colour cast may occur even with the more expensive filters, and there is some degradation of image quality. However, they are in our opinion useful in getting the right image in less than ideal light, and the occasional mild cast is easy to correct in post processing. Again, long exposure images are best in ideal natural light settings, but if this is not possible, the 10 stop ND filter allows the capture of motion such as in water or clouds even in bright daylight. The following images were taken using a 10 stop ND filter at about 4pm on a summer’s afternoon in Sydney.
Graduated ND filters. These we feel are an essential tool of the landscape photographer. Although the effect of graduated NDs can be reproduced in post processing, using the actual filters in capturing the image allows greater finesse in filter positioning and effect, as well as better control of exposure time. We use 1, 2 and 3 stop soft and hard graduated ND filters, as well as reverse graduated filters, the latter being particularly useful for sunrise and sunset shots, where the brightest area of the image is central. Of course you can stack these filters together for better control and versatility. Although some prefer to hand hold filters, we use a dedicated filter holder, designed for wide-angle lenses so that vignetting from the holder is avoided.
This image is exposed for the foreground which results in an overexposed sky, lacking detail.
With the use of a 3 stop reverse graduated ND filter, the sky is much better exposed, with the filter also allowing for a longer shutter speed and the depiction of movement in the clouds.
Other Filters. There are many other filters available which we either have not used or feel the effect is better replicated in post processing. We do have graduated coloured filters (sunrise and sunset sets), but feel that these often add unnatural or over the top hues to the image and have kept these on the shelf. Infrared filters also add another dimension to landscape photography, and we will look at trialing these in the near future.
For further reading, here is an excellent article on the use of filters in landscape photography:
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