Is a digital camera filter of any use or is this taken care of in your image editing software?

A couple of filters are must have

You might think a camera filter in the digital age is of no use. OK, some of the filter corrections can be post processed in Photoshop or other photo software but not all of them.

The most important camera filters

Of all the filters available, Polarizing filters and Neutral Density filters (ND) are very handy. To some extent you can do what the ND filter does in Photoshop or your preferred editing software. It is time consuming and dependent on the motive. So the best is to do the correction with the help of the camera filter at the time you take the photo.

The effect of the Polarizing filter however is not possible to achieve through the software, at least if you want a real effect. There are filters in Photoshop that can simulate the effect, but it will never be the same.

Polarizing filter

What does a Polarizing filter do?

After I got to know the Polarizing filters I always bring them with me. These filters are very useful when taking photos in bright conditions with blue sky with clouds. The sky becomes much more saturated and the clouds become slightly darker giving an overall better photo. The overall effect from the filter is the colors look more intense and shadows darker.

Also when shooting water this camera filter will avoid reflexes from the surface. The polarizing filter makes the surface more transparent. The same effect is achieved when taking photo of windows. The polarizing filter will make the window transparent so you don’t see the reflections. You will have most effect from the polarizing filter when you are at 90 degrees to the sun.

How to use a Polarizing filter

A Polarizing filter is either the filter thread screw in type with a rotating mount or the bigger square gelatin ones you fit into a filter holder which can be rotated. The circular Polarizing filters are the best option for modern digital cameras. These filters allow TTL metering and autofocus to be used. With the cheaper linear filters you will not be able to use the automatic measuring.

One side effect of the polarizing filter is that it absorbs light (likely 1,5 to 2 stops). In low light situations a slow shutter speed might be needed, and tripod will be essential. With the sun right behind you at 180 degrees, the effect of the polarization is almost non existent.

To get the wanted effect with a Polarizing filter, the filter has to be rotated in front of the lens. While looking through the viewfinder or on the LCD screen you can rotate the filter and see the effect instantly.

If your lens rotates the front elements while focusing, it will be more difficult to use a polarizing filter. In such a case you have to focus first and then place and rotate the filter for the best effect. The more expensive lenses have internal focus and do not rotate the front element.

The video below from www.dslrtips.com explains how to use a polarizing filter and the effects the filter have on your images

Camera filter tips

If you have a camera without filter threads (many compacts don’t) you can just hold the filter in front of the lens with your finger. This might be a little cumbersome, but if it is the only option, it will do.

When using a Polarizing filter you should be careful using lenses wider than 24 mm as you can risk some parts of the sky will get much darker than other part. You can certainly get strange effect if you take the polarization to the extreme.

Neutral Density filters (ND filter)

What is a ND filter?

The ND filter is a plain grey filter that will reduce the light coming on to the sensor. ND filters are available in different types that reduce the light from 1 – 3 stops. A filter that stops down 1-stop is called a ND2 while a 3-stops filter is called ND8. More than one filter can be combined to achieve the right conditions.

Using a ND filter is straight forward as you just mount it in front of the lens and shoot. The cameras automatic exposure and focus will still be working.

In which situations is a ND filter useful?

You want to use a slower shutter speed
If you take photos in very bright light conditions and you want to use a slow shutter speed to get the blurry effect of floating water, you might find the smallest aperture (highest number) and lowest possible ISO setting on your camera is not enough to avoid an overexposed photo. In this situation by using a ND filter that let inn less light might solve the problem.

You want to use a wider aperture
In bright light conditions you might want to use a wide aperture to get a shallow depth of field. This might not be possible in bright light, as your shortest shutter speed might not be enough to get a correct exposed photo. The ND filter again will be of great help.

The graduated neutral density filter

The graduated ND filter is similar to the above mentioned ND filter. The only difference is this filter is half clear and half grey colored. It is a filter commonly used in landscape photography where the sky often is very bright while the foreground is darker. The exposure in such a case will give an overexposed sky and perfect exposed foreground or vise versa. With a graduated ND filter this can be compensated.

This effect can be achieved in Photoshop or by shooting two exposures – one with the correct sky and one with the correct foreground. Later these tow pictures can be combined in the photo software.

The video below explain how to use a Graduated Neutral Density filter.

Which camera filter should you buy?

Both Polarizer filters and ND filter are available as screw-in filters or the square gelatin systems. As filters can be expensive, the screw-in type is ideal if you use the filter on one lens, or your lenses have the same filter thread (most likely they don’t). With the square systems, the same filter is used with all lenses. You only have to buy on adaptor ring for each of the filter threads on your lenses. For further reading I have put the links to the most reputed and known filter manufacturer's web sites below:

Cokin, Hoya, B+W, Lee and Tiffen



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