Australian_Photography_-_March_2016_

44 AUSTRALIANPHOTOGRAPHY.COM

HOW TO Which Filter?

RIGHT

A mid-strength four-stop neutral density filter allows

the water to blur just the right amount. Canon EOS

5D Mk II, 17-40mm f4L lens, 3.2s @ f/16, ISO 100.

BELOW

Mt Glorious, Qld, showing the effect of a polariser

(bottom) on green foliage on a cloudy day. Note the

reduced highlights on the leaves which allows the

‘greenness’ to show through. Canon EOS 5D, 17-

40mm f/4L lens @ 17mm, 20s @ f/11, ISO 100.

AUSTRALIAN PHOTOGRAPHY MARCH 2016

If you want that lovely cinematic minimum focus look you

need to use a wide aperture. However, in bright sunlight you

would have to use a shutter speed of 1/2000s to use an aperture

of f/2.8 or 1/8000s for f/1.4.

So what’s the problem, you ask. Well, to avoid that harsh

‘video’ look it’s usual to shoot what’s known as ‘180 degree

shutter’ which is 25fps at 1/50s or 50fps @ 1/100s so that frames

actually blur slightly into one another and give a smooth look

to movement. 1/50s at f2.8 will be totally overexposed in full

daylight unless you reduce the amount of light entering the lens

• cue the ND filter. An ND16 (4 stops) will allow you to shoot
  1/60s @ f4 in sunlight, or using an ND64 for 1/60s @ f1.4.
  The movie industry has been using NDs in this way for pretty
  much ever; in fact many decent video cameras even have built-
  in ND filters so you can set your shutter speeds and apertures
  almost independently of how much light there is.

Linear vs circular polarisers – what’s the difference?

A linear polariser passes through light that is polarised in a particular orientation.

Camera autofocus and metering systems can mis-read polarised light causing

incorrect exposures or focus – this depends on your camera brand and design.

A circular polarising filter is much the same thing but has what’s known as a ‘quarter-

wave plate’ glued to the back which, to put it simply, ‘unpolarises’ the light again. It still

reduces the intensity of polarised light entering the filter and is used in exactly the same

way, but will not effect the autofocus (AF) or metering of your camera.

If in doubt – buy a circular polariser.