Many cameras now feature advanced modes. These are shown on your cameras Mode Dial.Usually they will  be represented by the A, S and M letters. On Canon and Pentax cameras you might see Av, TV, and M.  I've already published an article on Aperture Priority, which is used to ensure either an image that is sharp from back to front, or one with a blurred background to make the subject stand out. Shutter Priority, as it's name suggests allows you to set the shutter speed and the camera sets the best aperture for the shot depending on the shutter speed chosen. To select this mode, turn your mode dial to the S or Tv position.
The purpose for setting the shutter speed is to ensure a sharp shot. Cheap entry level models usually have a highest shutter speed of under 1/500th of a second which will often be in sports mode. Cameras with the advanced modes will usually have a top speed of between 1/1000th and 1/4000th of a second. The slowest shutter speed will usually be between 15 and 30 seconds, although many high end bridge models will have a B or Bulb mode, which keeps the shutter open as long as the shutter button is pressed down. The longer the shutter is open, the more light is let onto the sensor, and if you are hand holding the camera introduces camera shake which produces blurred images. The faster the shutter speed is, the amount of light hitting the sensor is reduced, and the darker the image is, as well as being sharper. The left hand image to the right of this text is blurry, but with a faster shutter speed would have as sharp as the image to the right of it. Click on the images to preview them.
Slow shutter speeds are often used in night time photography to allow more light to hit the sensor. They require  the use of a tripod to avoid camera shake. The image on the left was taken with a relatively slow shutter speed of 2 seconds, Not only did this shutter speed allow a correctly exposed image, it ensured that the firework trails were perfectly captured. In sunlight, this shutter speed would produce an overexposed (completely white) image.If you've got a steady hand, a hand held shutter speed of 1/8th of a second or faster will usually ensure a sharp shot in sunlight. Under the same conditions in Auto mode, the camera will select a speed of between 1/200th - 1/500th of a second, and you should use this as a starting point. If your image is blurred or underexposed (too bright) then you need to select a faster shutter speed. If it's too dark, then you need to select a slower shutter speed to let more light onto the sensor.
However, there are times when lowering the shutter speed will produce a blurred image, and the slowest shutter speed that gives a sharp shot leaves an image that is dark. In this instance, you can use your camera's exposure button (a square with +/- in it or the letters EV) to add positive exposure compensation to the image which will make the shot brighter, or you can adjust the ISO setting higher, though be aware this can bring unwanted noise (grain) to your photographs. This picture of a Lancaster Bomber was taken with a speed of 1000/th of a second and is too dark. A slower shutter speed of around 1/200th of a second would have revealed more detail, but given a blurry image. If I had increased the EV setting by 1 then it would have been exposed better. Alternatively, increasing the ISO from 800 to 1600 or 3200 would have given a similar effect.
If your camera features image stabilisation, this will allow you to shoot at slower speeds and still get sharp shots. So instead of shooting at 1/60th of a second, you could shoot at 1/30th of a second and still stay sharp. Here's a quick guide to some commonly used hand held unstabilised shutter speeds by subject. Portraits 1/100th sec - 1/150th sec, Children running or football/rugby 1/200th sec - 1/250th second, Propeller aircraft 1/200th sec - 1/250th sec, Birds in flight 1/500th sec - 1/2000th sec, Jet aircraft 1/1000th sec - 1/2000th sec, cars handheld 1/500th  sec - 1/1000th sec, cars panning on tripod 1/50th sec - 1/200th sec. These are not definitive speeds, just suggestive ones. Depending on the available light, you might need to go a little faster or slower, Experimentation is the key here. Practice makes perfect.
blog comments powered by Disqus