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Monday, January 6, 2014

The Benefit of Filters

Digital cameras have reduced or eliminated the need for almost all filters. However there are still a number of filters that are important, and the effect of some of them are almost impossible to recreate digitally, either without a lot of time and effort, or at all. 

Circular Polariser
The circular polariser removes reflections from non-metallic surfaces such as grass and foliage, water, glass and the sky.  This filter will make a blue sky bluer, grass greener and even allow you to see beneath the surface reflections of water.  It has a moveable ring on the front that minimises or maximises the effect of the filter as you rotate it. The strength of the filter is also affected by the angle of the source of a reflection, and the angle of the main light source in relation to the camera and the subject. These can have a dramatic effect on your photo, with increased contrast and more saturated colours. 
The circular polariser is an important filter, because Photoshop can’t remove reflections and show what was behind a window or beneath the pond’s surface.

Graduated Filters
Graduated filters are still very relevant and useful to photographers.  The graduated neutral density filter (GND) is a square filter that sits in a holder (for example this Cokin GND Filter).  The filter is dark on one end and clear on the other.  This filter is used when a scene has a very bright horizon but a dark foreground.  A normal exposure that averages out the brightness levels in a scene will either blow out the highlights, losing detail in the sky, or underexpose, losing detail in the foreground.  A normal exposure would not result in a properly exposed image across the frame.  A GND filter works when the photographer positions the dark part of the filter over the brightest part of the image (eg the sky), reducing the brightness in this part of the image.  This allows the camera to capture detail across the entire image with one exposure.  GND filters also come in different colours for slightly different effects.

Neutral Density Filter
The Neutral Density filter (ND), reduces the amount of light that passes through it. It does a similar job to the GND filter except that it darkens the entire image.  This is useful in bright situations where you need a slow shutter speed but there is too much light around for your ISO and aperture to handle.  This is valuable in situations such as a waterfall when you want the water to appear silky instead of as frozen drops.  If there is too much light on the scene you may not be able to slow the shutter speed down enough to make the water smooth and still get a well exposed photo.  Using an ND filter will allow you to use a slower shutter speed. 
ND filters come in various densities from 1 stop of light up to 9 stops of light.  They are described as ND2 (1 stop), ND4 (2 stops), ND8 (3 stops) and ND400 (a whopping 9 stops). 

Variable Neutral Density Filter
The Variable ND can vary its light stopping ability generally from an ND 2 up to an ND400 simply by spinning the front glass on the filter.  This is very handy, as focusing can be very difficult at ND400.  This filter allows you to focus at ND2 and adjust to whatever darkness you need.    Hoya and Cokin both make them.

UV Filter
The clear UV filter is not an effects filter, but is the one filter than almost every photographer uses.  A similar filter though less common is the protector filter.  UV filters were originally used to clear haze from landscape and similar photographs as film was particularly sensitive to UV light.  Digital sensors now have UV filtration on them so the UV filtering ability is no longer required.  The reason these filters are still used is primarily for protection of the front lens of your camera.  It is always cheaper to replace a filter than it is to replace a lens or front element of a lens.  The most common mistake people make is not matching the quality of the filter with the quality of the lens.  Be prepared to spend approximately 10% of the price of your lens on your filter.  Here is a range of UV filters to suite any budget.

Each of the filters described above are useful because they are impossible to create in a computer program, or they would take a very long time to replicate. 
If you have never tried these filters, come in to one of our stores or give us a call and we will guide you in the right direction to turn your ideas into reality!

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