The Shutter

The camera’s Shutter is one of the three components of the Exposure TriangleExposure Triangle. Its role is to regulate the time the media is exposed to the light whether it is Film or Digital photography. Nothing has changed at the shutter level since the arrival of Digital photography, except maybe the burst mode and we talk about that in a future video and post. The exposition time is usually expressed in fraction of a second, in second and some cases in hours ( hundreds of seconds). Most DSLR would offer you the possibility to fire the shutter at a maximum speed of 1/8000 sec which you would agree is quite fast and if in some rare occasion this would not be enough you could always use a Neutral Density filter but will cover this in another video and post. On the opposite side of the scale, most DSLR would offer the possibility to use set a time value of 30 sec. To achieve a longer exposition, you would need to use the Bulb mode which we will cover as well in another video and post.

How the time scale works

1sec, 1/2 sec, 1/4 sec, 1/8 sec, 1/15 sec, 1/30 sec, 1/60 sec, 1/125 sec, 1/250 sec, 1/500 sec,  1/1000 sec, 1/2000 sec, 1/4000 sec, 1/8000 sec. Each time you increase the firing speed to its next value, we call it a stop (just like for the ISO as seen in the ISO). Some cameras will let you increment the Time value by a 1/2 stop or even 1/3 stop to give you more flexibility in your exposure. Each time you either reduce or increase the Time value by a full stop you, in fact, double or divide the exposition time by 2. Subsequently, this means you, in fact, double or divide by two the amount of information coming from the light. Here are some sample exposures I shot as small JPEG, and they aren’t post processed:

So you may be asking yourself: then what Time value should I use and when?

Well just as with the ISO it all depends on of the condition you are shooting under. As a matter of a fact, if you are under a lot of light then you may need to use a fast Shutter speed to reduce the amount of information and avoid your exposure to be over exposed. Subsequently, if you are in a dark place like a restaurant or even doing Night photography, you may need to slow down the Shutter speed (i.e several second or minutes). The above explanation is not exhaustive and is only intended to help us understand the basics of photography. Indeed, alike with the ISO, there is some occasion when you would use a slow shutter speed in bright day light, but this will be covered in future videos and post when we learn to achieve a Correct Creative Exposure.

Be aware of one drawback when using slow Shutter Speed: The Blur.

When slowing down the shutter, you may notice some blur in your exposure. This is normal, and your camera is certainly not to be blamed for it. This statement is based on two assumptions:

1. You are either hand holding your camera
2. Or you are on a tripod, but you have left the Lens Image Stabilisation turned on.

In the option 1, being human, it is very difficult to stay still, and this is even truer when carrying/holding an object. So you may ask how slow can I go while hand holding my camera. Well once again it depends on of you (i.e. how many Redbull or coffee cup you had) but since you are craving for a rule of thumb here it is:

Your Shutter speed should not be slower than 1/your Lens Focal Length *

You are then going to ask yourself, what the heck is the Lens Focal Length? We will cover this in another video and post but for now, just know that you will find that length from the number showing on the top of your lens like this (in this case being 24mm):

In the case of the Lens Focal Length selected in my image above, 24mm, the slowest Shutter speed I can use while hand holding the camera is 1/24 which is not exactly on Time value scale we have above so the closest value is just fine, hence 1/30 sec. * Note that this rule is assuming you have a Full Frame camera. Is this term does not tell you anything, I invite you to see the post on the History of Photography.  Therefore in my case, since I use a Canon 60D which is not a Full Frame camera but has a Cropped Sensor ( as all Canon DSLR) of 1.6 here is the rule I use: 1/(24×1.6) = 1/38.4 so I would go finally with 1/60 sec. In option 2 ( Lens Image Stabilisation turned on), the stabiliser will constantly try to adjust any shaking even if there aren’t any which result in some blur. We will cover Lens Image Stabiliser in a future video and post when covering Lenses. Note that it is nearly yet impossible to eliminate or reduce blur in exposure in post production. Although that being said at Adobe Max 2011, there has been a sneak peek of a new feature for the next Photoshop CS6 that should help to reduce the blurriness of some images. This is all for this post. If you have any question, do not hesitate to put it in the comment box below.