My Long Exposure Technique
Long Exposure photography generally means using a shutter speed long enough to record some form of movement in a scene. In theory this could be anything longer than 1/30 of a second. In practice typical long exposures will range from a few seconds up to many minutes depending on the light conditions, subject and the effect the photographer is after. I have been using this technique for several years now across a range of landscape and architectural photography and I love the effect. The aim of this article is to share some of the knowledge that I have gained in this time and to illustrate it with some of my images.
The essence of the Long Exposure (LE) technique is to have the camera’s shutter open long enough to record something moving in the scene as a blur. This blur can add a sense of movement and dynamism to an otherwise static scene. I find that having areas of an image that are sharp and static, along with areas of movement give the best effect.
A tripod is essential, with exposures of several seconds or more hand holding or using a monopod just isn’t going to work. Choosing a tripod is always a matter of weight. The heavier the better for stability purposes, the lighter the better for carting your gear up a mountain. I have several of varying weights depending on where I’m going or how strong I’m feeling. There is also a wide choice of tripod heads including, pan & tilt, ball or geared. My currently favoured set-up is a Manfrotto 055 carbon fibre tripod with an RC2 ball head which is quite a compact lightweight combination but stable enough for most ground level applications.
Cameras are designed in general to record sharp images in a range of daylight conditions. In order to extend exposure times in daylight it’s normally necessary to use a specific filter to reduce the amount of light entering the lens. These are called Neutral Density filters and are available as circular screw on types or rectangular system types such as those made by Cokin or Lee. Good ND filters should reduce the amount of light without adding any form of colour cast. Some cheaper filters do add a red or blue cast and whilst easily removed in post processing, it’s not ideal if you can help it.
ND filters are either described by the number of stops they reduce light by, i.e. 6 stop or 10 stop or by the number of times the light is reduced by i.e. ND4 reduces light by 4 times (equivalent to 2 stops) or ND16 reduces light by 16 times (equivalent to 4 stops). I prefer to stick to talking in stops as it’s easier to deal with. I started off my LE work with a single screw in 10 stop Hoya filter. I now have a set of Formatt-Hitech filters which cover 3, 6, 10 and 16 stops. This gives me the option to set shutter speeds to more or less anywhere I want for a wide range of conditions. If you’re trying this technique for the first time then a cheap e-bay set can do the job, or some people swear by holding a piece of dark welding glass over the lens.
A cable release is also useful, in particular one with the ability to lock the shutter when using the ‘B’ or bulb mode. A means of covering over the camera eyepiece when making particularly long exposures is also handy.
There are no hard and fast rules regarding the best shutter speeds for LE photography. It is very dependent on the scene, weather conditions and the effect required. I have discussed some types of subject below along with examples. My normal process is as follows, I typically take some test shots hand held in aperture priority auto until I get a composition I’m happy with. I will then set up the tripod so the camera is in more or less the same position and then take some more auto test shots to ensure focus, and exposure. I will then switch image stabilisation and auto focus off on the lens. Working from the metered exposure I will then increase the exposure and put on the appropriate ND filter. I’d work out my rough exposure as follows:
If I metered normally and got 1/250 @ f8, adding an ND filter would change the shutter speed as follows:
So my trusty 10 stop would give me an exposure of 4" @ f8
I would then switch to Manual or Bulb mode and would use this exposure as a starting point, review the histogram and tweak as necessary including changing shutter speed and if needed aperture and ISO.
Waterfalls often only need half a second to give a sense of movement and if the exposure is too long, then any detail can be lost entirely. With waves, again it depends if you want the absolutely smooth milky effect or want to retain some detail in the waves. Details are maintained up to around 10 secs, 30 seconds or more will normally give an entirely smooth effect.
Beach at Hornsea - 4secs @f/8 ISO100, 10 stop ND
Aysgarth Falls, Yorkshire - 2secs @f/11 ISO200, 10 stop ND
Clevedon Pier - 30secs @f/22 ISO100, 10 stop ND
Cloud movement is entirely dependent on the weather, wind speed and the effect also depends on the wind direction in relation to what you’re trying to capture. Sometimes 10-20 seconds is enough, other times several minutes are needed. The best skies are blue skies with limited white clouds that are moving well. Getting up early is often good, as I tend to found the skies are often clear, but clouds build up as the sun comes up.
Withernsea Lighthouse - 30secs @f/11 ISO200, 10 stop ND
Imperial War Museum North, Manchester - 24secs @f/11 ISO200, 10 stop ND
Town Docks Museum, Hull - 110secs @f/8 ISO200, 16 stop ND
A well as water other things that move in the wind can add a dynamic effect, smoke, flags moving grass, light trails, etc
Eggborough Power Station - 20secs @f/18 ISO100, 10 stop ND
Spurn Lightship, Hull - 10secs @f/8 ISO200, 10 stop ND
Humber Bridge - 5secs @f/8 ISO200, 10 stop ND
I hope this has given you an insight into Long Exposure photography, if you've enjoyed the article, please leave a message on my guestbook page, or follow me on Facebook. My page is: https://www.facebook.com/stevecheethamphotography
No comments posted.