Tuesday, May 19, 2009

DSLR Tips: How to blur water for a creative effect

When it comes to photographing moving subjects, you’d naturally assume freezing the action would give the best result. That’s certainly the case for some subjects, but others can end up looking static and lifeless. Waterfalls and rivers are classic examples which can take on a far more dramatic appearance when the water itself is blurred.

In the photo above left, we’ve used the camera’s automatic settings, and a relatively quick exposure has frozen the water in its tracks – as a result it looks lifeless. In the photo above right, we’ve adjusted the shutter speed for a slower exposure which has blurred the water, giving both a dreamy appearance and a far greater impression of motion. In our video tutorial below, we’ll explain how to achieve this effect, and at the bottom of the page you’ll find a reminder of the steps you’ll need to take.

Checklist: Blurring water for a creative effect

1: Switch your camera to Shutter Priority mode by turning the mode dial to ‘S’ or on Canon models, ‘Tv’.

2: Choose a slower than normal shutter speed to blur the water. 1/30 is a good starting point.

3: Check your photo. If the water isn’t blurred enough, choose a slower shutter speed like 1/15 or 1/8. Note you may need a tripod or an anti-shake system to avoid camera shake – see below.

4: In shutter priority, your camera will work out the aperture setting for you. If the f-number starts flashing though, it means it can’t balance the shot. In this example, the exposure may be too long, so if your sensitivity (ISO) is already at the lowest number, you’ll have to choose a slightly quicker shutter speed until the f-number stops flashing.

5: After taking your photo, remember to set the mode dial back to Auto or Program mode.


Watch out!

As you reduce the shutter speed, you become more susceptible to camera shake. People vary, but if you’re using a kit lens zoomed-out to wide angle without any kind of anti-shake, the slowest handheld exposure you’ll normally get away with is about 1/30. If you naturally shake, you may need at least 1/60, but if you’re very steady, then you may be ok at 1/15. If you zoom-in at all, you’ll need faster exposures to compensate for the greater magnification.

So when applying this technique to blur water, always hold your camera very steady. Tripods can provide a steady base, or alternatively cameras and lenses with anti-shake facilities can greatly help here – see below. If you are using a tripod, remember pressing the shutter release button can still wobble your shot. So always take the photo with either a shutter release cable or the self-timer to avoid all chance of shake.


Equipment tip

The simplest way to avoid camera shake is to use a tripod. Manfrotto models are widely regarded as the best around and allow you to separately buy the legs and the head unit. A great starter combination are the Manfrotto 190-series legs and the 460MG head unit. If you’d prefer to travel lighter, consider a Joby Gorillapod who’s flexible legs can be wrapped around almost anything from a railing to a branch for a steady grip.

Anti-shake facilities are now being built into many DSLRs and lenses. These allow you to handhold much slower exposures than normal, although for the longest you’ll still need a tripod. If you’re a Canon or Nikon DSLR owner, popular lenses with anti-shake include the following:

Canon EF-S 17-85mm IS USM review

Nikkor DX 18-200mm VR review


Watch out! Too bright? Use a 'Neutral Density' filter

As you select slower exposures in Shutter Priority mode to blur action, your camera will automatically close the iris in the lens in order to maintain a correct exposure. So far so good, but at a certain point, the iris will be at its smallest size, beyond which slower shutter speeds will mean an over-exposed image. When this happens, you'll normally see your aperture f-number start flashing as a warning your camera can't balance the exposure.

This can be a problem if you're trying to use the blurring technique on a bright subject as even with the aperture closed to its smallest opening, the shutter speed for a correct exposure may still end up being too quick to blur the motion.

Presuming your camera is already set to its lowest sensitivity (the smallest ISO number), the solution is to attach a special filter onto your lens which blocks some of the light. Since these filters only reduce the light entering the camera and don't affect the colour, they're known as 'Neutral Density' filters.

A 2x Neutral Density filter will halve the light entering your camera, while a 4x will quarter it. They're very handy accessories to have if you like the technique described on this page. Simply buy a model with a screw thread which matches your lens - most DSLR kit lenses have a filter thread diameter of 58mm, but it will always be written on the front of the lens.

A polarising filter can also act as a Neutral Density filter, although depending on its position and the surroundings, it may have other effects too. Either way, both types of filter reduce the light entering your camera, allowing you to use slower shutter speeds without suffering from overexposure.

No comments:

Post a Comment