Welcome back for the second part of the beginners guide to your camera series. This part will focus on the shutter speed and how it effects photographs and your flash. If you have not read the first part in the series I recommend you do so. I go over some of the basics of selecting modes on your camera. I also explain the aperture mode and how to best use it.
The Shutter Speed
The shutter mode on your camera is most often represented by the letter “S” or “Tv”. When using this mode you tell the camera a specific shutter speed to use and the camera does the rest. Often the shutter speed is displayed as a large whole number. You can think of this number as itself over 1. So if your camera is displaying 250, in reality it is 1/250 or two hundred fiftieth of a second. Unless you are shooting in a low light environment without a flash your shutter speed should be less than one second.
What does this mean specifically? This number is telling you the amount of time the shutter will be open during the exposure. The larger the number the less time the shutter will be open (1/60 of a second vs 1/800 of a second). This has several effect on your final photograph. First if your shutter is open longer the more light it will let in. This can lead to brighter photographs in very dark environments. However we also know that the aperture has the same effect. If the aperture is open wider it lets more light in as well.
The shutter speed effects your photographs in one other way as well. It can allow you to better “stop time”. If you have a fast moving subject and you want the photograph to be sharp then you should use a fast shutter speed. With the shutter open for a shorter amount of time, your camera is exposed to less movement of your subject. A good example of this is to take two photographs of moving water (like a waterfall or from a hose) outside where you can get plenty of light. User shutter priority mode and take one photo with a slow shutter (around 1/30) and another one with a fast shutter (around 1/1000). Assuming it is a sunny day you should get two similarly exposed photos but with very different looks of the water.
The same idea of motion blur in your subjects can be translated into motion blur from camera shake. The same way a slow shutter speed can create blur in fast moving subjects, it can also create blur from you moving the camera while the shutter is open. Camera shake blur most often happens when you try and take a photo indoors without a flash. Normal room lighting is not adequate enough for your camera to use a fast enough shutter speed for hand holding. Some people have a steady hand and can hold the camera very still so the specific speed at which you start to see camera shake blur will be different from others.
This leads to my final thought on shutter speed. You may have noticed when you connect a flash or use a flash with your camera you are limited to a maximum shutter speed. This is called your camera’s maximum flash sync speed. I am going to get a little technical for a second. The shutter on most digital cameras are created with two collapsible dividers, one on each side of the digital sensor. The shutter speed, up to your max flash sync speed, is created by the first divider opening and exposing the sensor for the correct amount of time and the second divider closing just before the time as elapsed. This allows the whole sensor to be exposed at one time. Speeds faster than the max sync speed are created by the first divider opening but before it finishes the second divider starts to close on it’s tail. This allows the sensor to be exposed for the correct amount of time however the whole sensor is never exposed at the same. Instead only the slit between the dividers exposes the sensor as it passes.
Why does this matter when using a flash? Well your flash bulb is only lit up for a very small amount of time. So this means that if you use a speed above your max flash sync the light from the flash will only be exposed on part of the sensor as the shutters move across (or not at all depending on if it fires to soon or late). This also means that when using a flash changing the shutter speed does not effect the brightness of the flash. If you use 1/60 or 1/200 the same amount of light will be put out from the flash. However you can use your aperture to effect the brightness of your flash, because the aperture constricts the opening of light to the sensor.
I could talk about flashes a whole lot more but that is for another article. If you have any questions please leave a comment and I hope this helped you with the basic understanding of shutter speed.