Let's start with some extra context. When you first start using a camera, one of the main areas to concentrate on is ensuring that very elements of the image you take is sharp, and this means using the right shutter speed.
For scenes where nothing is moving the only thing that matters is that the shutter speed is fast enough to compensate for any movement you might make while the shutter is open.
This is known as ‘camera shake’ and can result is a blurred or slightly fuzzy-looking image.
To guarantee a sharp shot in these circumstances, aim for 1/100 as a minimum – although with modern cameras that have great image stabilisation, you can sometimes get away with less. It’s just a case of seeing what works for you an your camera, so experiment with different shutter speeds and see how low you can go before your shots stop being sharp!
The fun begins when you have elements in the scene that are moving – which may just be a flower or a tree blowing in the wind, but could be a person, car, boat or train moving at speed.
In these situations you have two options, you can either ‘freeze’ the action so the moving element looks sharp, or you can allow some blur to be captured, to give the feeling of movement.
To freeze the action you need a fast shutter speed – and how fast that is depends on how fast the subject is moving.
For example 1/250 might be enough to stop a flower blowing gently in the wind, or to avoid blur when shooting a portrait where the subject might move slightly. But for a dog leaping to catch a ball, or a cyclist whizzing past at speed, you may need 1/1000 or more.
Working in aperture priority, this means choosing your aperture to suit the scene, framing the shot and checking the shutter speed, and then increasing your ISO until the shutter speed comes up to the level you need.
They key thing to remember with fast shutter speeds is that you are reducing the amount of light that hits the sensor. So you have to compensate by choosing a wider aperture (which may not be ideal for the type of shot, as you will lose depth of field) or by increasing your ISO, which can result in a noisy or grainy image.
These are the compromises that have to be made, and it’s up to you as the photographer as to which settings you choose. Remembering that grain is always better than unwanted blur, and that there are many excellent ‘denoise’ software options available.
To capture motion, you need to go to the other end of the scale by choosing a slower shutter speed (also known as a ‘long exposure’). This allows for movement to take place while the shutter is open, and so creates a streaky ‘motion blur’ type effect on the subject.
So for example, a waterfall where the water looks soft and streaky rather than having frozen droplets, or a street scene where the people are visible, but blurred – maybe to illustrate ‘rush hour’.
Another artistic option with longer exposures is to capture car headlight and tail light shots at night. With these types of images the exposure is so long that the cars disappears completely and all you see are the light trails they leave behind.
The key to a successful motion blur image is that the elements of the scene which are not moving remain sharp – meaning you almost always have to use a tripod or other stable surface, unless you have very steady hands!
Realistically you’re aiming for a shutter speed of half a second or longer, and often a lot longer, to create any type of motion blur. The actual speed required will depend entirely on how fast the subject is moving, and how much blur you want to create.
The other issue is that daytime shots will over expose if using very long exposures (slow shutter speeds) as too much light hits the sensor, even if you use a narrow aperture and a low ISO. In these cases you have to use something called a Neutral Density (ND) filter which is like sunglasses for your camera - cutting out light, so you can shoot long exposure shots in the daytime without over-exposing.
For this reason, it’s a good idea to experiment with long exposures at night first, as the much lower light levels mean you don’t have to worry about over exposing your shot.
Working in aperture priority, choose your aperture to suit the scene in the first instance and set your ISO as low as it will go.
Then frame the shot and check your shutter speed. If you are working in low light, then your shutter speed may be slow enough for what you want already (maybe half a second to blur people walking along the street) – but if you want a much slower shutter speed (for example 10 seconds to capture car light trails) then you can make it even slower by selecting a narrower aperture.
This cuts out more light and so requires a longer exposure – but the narrower aperture will not adversely affect your shot in other ways. In fact, narrow apertures on urban night shots create lovely starbursts on points of light, which is an added bonus!
​
Return to the PTiYP app to continue.
For information on my 1-2-1 tuition services - which are available in person, or online via Zoom - please visit my photography tuition page.
I can help with anything from off-auto level tuition and learning how operate your specific camera, through to advanced skills, image editing and portfolio reviews.