What is shutter speed.?
Sounds like a bit of an obvious question, don’t you think..? shutter speed is the speed of the camera shutter….!
Ok we get that, but what does it mean and why do we care…?
Right then you want to really understand… well there will be some hard bits ahead so sit tight..
Start right at the basics…. what is the camera shutter..?
In your shiny new camera there are two things which determine how much light enters through your lens and falls onto your camera sensor, thus exposing your pic; the aperture (adjustable hole in the camera lens) and the shutter.
Imagine the shutter as a ‘Door’ in your camera body, when open it will allow the light through onto the camera sensor and when shut it will stop the light. This door (shutter) can be opened and closed for a period of time, which you can control. The longer the door is open the more light falls on the camera sensor and exposes the picture.
You could stop now….. you got the basic principle…!
No.. I hear you say… we want to know why our camera has loads of different shutter speeds and why would we change them…
Different shutter speeds are used to achieve different results. In one hand it is a way to control exposure, but in the other hand it is a creative tool.
Told you it was going to get harder.
Lets start with the best bit…. how to use the right shutter speed to get the result you were looking for. We start with fast shutter speeds…. why do i need a fast shutter speed..?
The best way to get this clear in your mind is with a practical example, so lets go extreme. You are at the formula one race track in a perfect position to get the cars whizzing past you at 200mph. You would like to take super sharp images of the cars as they pass, that is the end result you are aiming for.
Lets just pause and think logically, if i am going to open my shutter for a long time (a long exposure) a SLOW shutter speed, lets say one second, for this shot, it would make sense that during this one second period the shutter (door) is open the car would have moved, therefore the light from the image would not be stationary and your image would be blurred….. did that make sense..? to capture the cars i need a FAST shutter speed, in the region of thousands of a second, so when the shutter (door) is open it is so fast the car would have moved an insignificant amount that it will look stationary and your image will be sharp.
Let us now go to the other extreme, you would like to capture a firework display, your aim is to capture the pretty trailing light as the fireworks drop from the skies. Again pause and think logically, the light from the fireworks will normally last a few seconds, so if my shutter speed was super fast, i would only get very little light and no firework show (plus you would struggle with the low light, but that is another blog), therefore for this type of shot you would need a very SLOW shutter, maybe a number of seconds. so slow that a tripod would be required to keep your camera still.
Again.. you could stop now.. you will have a good idea why we have fast and slow shutter speeds..
But if you want to know the relationship between shutter speed and aperture to get the right exposure, you need to read on….!
We did mention earlier that the lens aperture and the shutter speed can control the amount of light exposing your camera sensor and thus determine the exposure of your image. for this bit i am going to be brief as in starts to overlap on other blogs (see f/stop blog and ISO blog).
To keep it simple i want you to think about your camera sensor and how light determines how your image will look. If you expose your camera sensor to a lot of light for a long period of time it is likely the outcome will be a very over exposed image, and if you expose the sensor to very little light for a short period of time the image is likely to be very dark…… just keep this principle in mind.
The aperture in your lens is an adjustable hole which can be made big to small in very specific steps (f/stops). When it is a big hole it lets in loads of light through the lens, when it is small it limits the light through the lens. These different apertures will give your image different effects, like depth of field, but don’t worry about this, just accept we like to use different apertures……. what as this got to do with shutter speed..?
I am getting there.. trust me…
The shutter speed and aperture work together to make sure your camera sensor receives the right amount of light to achieve the exposure you are aiming for. So for example if i choose an aperture where the hole is big and loads of light is entering the lens, this may be too much light and will result in an over exposed image, so what i can do is increase the shutter speed, so limiting the period of time the sensor is exposed to this light, thus controlling my exposure….. obviously it works the other way to, if you choose an aperture where the hole is small, only a little light will enter the lens , therefore you may need a slow shutter speed to increase the time the sensor is exposed to the light.
I can hear you all scream… but what if i don’t want that shutter speed…. or what if the aperture is not the one i want to use for depth of field, how do i get the right exposure..?
This is what photography is all about… you have tools like aperture control, shutter speed and ISO to name a few, which once you understand the principles you can adjust these combinations to get the creative results you had in mind, with perfectly exposed images.
There is so much more to shutter speed, but we will save these for more blogs. The purpose of this blog is for you to grasp the following concept:
Shutter speed can help control the exposure of an image.
Shutter speeds can be adjusted fast and slow to help get the right shot in difficult conditions.
Shutter speeds can be adjusted fast and slow to allow creative results.