20 August 2018
PART 2: THE NEED FOR SPEED - THE USE OF SHUTTER SPEED SETTINGS IN WILDLIFE PHOTOGRAPHY

Today we continue with part two of Chad Cocking's The Need for Speed – The Use of Shutter Speed Settings in Wildlife Photography.

As we have mentioned before, knowing your camera whilst on an African safari makes a huge difference between an average photo, and a brilliant one.

We have already seen how by increasing our aperture to the smallest f-number is going to allow the most light through any given lens, and this can help to increase shutter speeds. There is a direct relationship between changes in aperture and shutter speed. A change in one will lead to a concurrent change in the other. At the risk of getting too technical, it is worth illustrating this point so that one can see how the opening up of one’s aperture can give one increasingly faster shutter speeds. For example, if a correct exposure for a particular scene is measured at 1/60 second at f/8.0, we can then increase this relatively slow shutter speed by changing our aperture:

  • An aperture of f/7.1 will have a shutter speed of 1/80 second
  • An aperture of f/6.3 will have a shutter speed of 1/100 second
  • An aperture of f/5.6 will have a shutter speed of 1/125 second
  • An aperture of f/5.0 will have a shutter speed of 1/160 second
  • An aperture of f/4.5 will have a shutter speed of 1/200 second
  • An aperture of f/4.0 will have a shutter speed of 1/250 second
  • An aperture of f/2.8 will have a shutter speed of 1/500 second

From these numbers above, we can see how for every extra full stop of light (shown in bold) we allow through the lens, our shutter speed doubles in speed. Depending on the maximum aperture of your lens, this can allow you to get considerably faster speeds with the aperture wide open. This is the very reason that I will personally recommend shooting with at the smallest f-number you can.

The only problem with the above figures is that the really fast shutter speeds only come at apertures of f/4.0 to f/2.8. Unless you have invested good money in your equipment, you are most likely going to have a lens with maximum aperture of f/5.6. So, what does one do if there is still a need for a faster shutter speed? The simple solution is provided for us by the camera’s ability to alter its sensitivity to light. This is achieved by increasing the ISO settings of the camera.

Although this topic will be dealt with in more detail in the next blog, for now it is only relevant for us to know that as we increase our ISO value, we increase our camera’s sensitivity to light. The more sensitive it is to the light, the less light is needed to achieve a correct exposure. As a result, we are able to shoot with a faster shutter speed and reduce our chances of motion blur in the resulting image. For each doubling of our ISO (an increase of one full stop), we can clearly see how there is a concurrent doubling of shutter speed. Carrying on with the above example, we can see how ISO affects shutter speeds as follows:

  • An aperture of f/8.0 at ISO 100 will have a shutter speed of 1/60 second
  • An aperture of f/8.0 at ISO 200 will have a shutter speed of 1/125 second
  • An aperture of f/8.0 at ISO 400 will have a shutter speed of 1/250 second
  • An aperture of f/8.0 at ISO 800 will have a shutter speed of 1/500 second

This image was shot at an ISO of 1600 to ensure that there was a fast enough shutter speed to capture the hippo exploding out of the water. If it was shot at too low an ISO, the image would have suffered from motion blur of the subject

Having read all of this, one might be tempted to ask the question of why, if we want a faster shutter speed, don’t we just dial that fast shutter speed into the camera and let it choose the appropriate aperture and ISO to give me the correct exposure? The answer to this is that this is most definitely possible if you are shooting in shutter priority mode on the camera (delineated as S on Nikon or Tv – for Time Value – on Canon). It is however a technique that I have never been a fan of for the following reason. If you select a shutter speed that is too fast for the available light, and the lens’s aperture cannot open up any wider to let more light in, then what will the result be?

The simple answer is a dark, under-exposed image. Newer cameras that have an auto-ISO function may help prevent this by automatically increasing the ISO if the aperture can’t be increased anymore. We will see in the next blog, having a very high ISO value is not without negative consequences. As a result, my preference for achieving the fastest possible shutter speed will always be to shoot in aperture priority with the aperture wide open to allow the most light in. I would then manually adjust my ISO to a level that I am most comfortable with. If it gets beyond a point where I cannot get a fast-enough shutter speed to freeze the action, I either simply put the camera down and enjoy the scene before me, or I try and get creative with some low-light panning.

The only time that I ever dial in a shutter speed and let the camera determine the other settings is when I am going for such a low-light panning shot. This is a technique whereby you intentionally select a slow shutter speed, and while shooting, move the camera in an attempt to follow the movement of the animal. If you get it just right and move the camera at the same speed as the animal so that it doesn’t appear to move relative to the pane of the camera. You end up with a relatively clear subject against a blurry, motion-filled background (which was moving, at least in relation to the camera’s sensor). I have always found this method to be a hit- or-miss affair, and one that requires not only a good level of skill and practice, but also a large amount of experimentation.

This panning shot of a young hyena was photographed at 1/30 second as it ran after one of its clan mates. As the light was already low, I simply kept the ISO low at 400, and an aperture of f/5.6

To achieve a slow shutter speed to pan with this zebra in bright late-morning light, the smallest aperture of f/32 was selected with an ISO of only 50. Together, this gave a shutter speed of 1/5 second to achieve the motion blur.

A suggestion would be to start off with a shutter speed of around 1/50 to 1/60 second and evaluate the results from there. If there is too much blur, set the shutter speed faster (say, 1/100). If there is not enough blur, then slow the shutter speed down even more.

There are so many factors that affect the level of blur that it is impossible to give one standard setting to use. The focal length of the lens, speed of the animals movement and the distance of the animal from the camera. All of these factors are going to have a role to play in determining what settings you need to use. Yes, you risk ending up with a memory card full of blurry images that all get deleted, but you also have a chance of capturing something different. Something that really shows and expresses the movement of the animal you are photographing. So go out there and give it a try!

A less successful panning attempt where the shutter speed of 1/15 second was too slow to capture any detail of this leopard jumping out of a tree.

For now though, that is enough about shutter speeds for this blog. In our next blog in this series, we will be looking at how we can use the cameras ISO capabilities to get more out of our wildlife photography, so until then, happy shooting!

A shutter speed of 1/4000 second allowed the action to be frozen as this leopard descended a Knobthorn tree.

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