When using a digital camera, whether you’re aware of it not, four factors come into play. These four factors are:
I will try to explain each of these things in the simplest way possible. So, first off is aperture. Aperture is simply a posh word for the opening of the lens. The wider the opening, the more light it allows to reach the camera’s sensor. A wider opening is dictated by a low f-stop, such as f/1.4 where a narrower f-stop is dictated by a larger f-stop, such as f/11.
The names of lenses state the maximum opening of the lens. It is better to have a lens with a larger maximum aperture as the opening can be “stopped down” or made smaller. An f/1.4 lens can be stopped down to f/4 but a lens with maximum aperture f/4 cannot achieve an f-stop of f/1.4.
A fast lens can create separation of the subject from the background. Below is a picture of me being silly.
Do you see how I am sharp and in focus while the background is blurred smoothly? This is achieved by having a faster lens, in this case f/1.4. Portraits and sport photography generally warrant a shallow depth of field (DOF) as well call it. It rids the picture of any distractions.
The quality of blur is referred to as ‘bokeh’. Many people refer to the circles that appear when the pictures are out of focus (OOF) as bokeh. I just call them bokeh circles. Notice the left side of the picture above. You can see the circles slightly: the white and gold circles. These circles appear when there is a light source, or in this case a reflective surface.
While sport photography pictures may look better with a shallower depth of field, the opposite holds true for pictures where you want everything to appear sharp and in focus, such as landscapes.
Below is another silly picture of me.
In contrast with the previous image, notice how there are no bokeh circles and how me, the tree and even the escalators in the back are all in focus. This is achieved by stopping down the lens’ aperture (ie, f/11). Of course by making the opening of the lens smaller, you are also restricting the amount of light that is allowed to hit the camera’s sensor. If there’s less light, you are likely to have what is called as motion blur, usually an unwarranted type of blur.
It should be noted that aperture, shutter speed and ISO work hand in hand. When one of them changes, one or both of the others have to be changed to compensate.
So motion blur. This relates to shutter speed. Shutter speed is a pretty simple concept and most people seem to understand this the easiest. It is basically how fast the sensor is exposed to the light entering from the lens. By having a slower shutter speed, more is allowed to hit the sensor. When you need to have a deep DOF (f/11 such as for landscapes) and the small aperture lessens the amount of light that is entered through, you can compensate by having a slower shutter speed.
However, a slower shutter speed leads to motion blur and camera shake.
Notice in this picture how only the people in the purple and blue are blurry. This is because my shutter speed was too slow. This is called motion blur. The shutter of my camera was opened for too long of a time (in this case 1/30 of a second). So, during the 1/30th of a second that the shutter of my camera was open, the people moved. I could have increased my shutter speed to prevent this motion blur.
Below is an example blur due to camera shake.
This is the result of not holding the camera steady enough. Because it was so dark outside, even with my lens wide open, the camera had to use a slower shutter speed to capture the image. In this case, the shutter speed was 1/8th of a second. I couldn’t hold the camera steady for that amount of time when the shutter was open, hence blur due to camera shake.
It is generally a rule of thumb to have your shutter speed set at the reciprocal of your focal length to avoid camera shake. For example, if I had a 50mm lens, I should set the shutter speed to at least 1/50th of a second; if i had a 600mm lens, I should set the shutter speed to at least 1/600th of a second. Again, to remedy this, I should just increase my shutter speed. And the drawback of this is that it lets in less light.
So what do you do when you have your lens wide open and at a shutter speed that’s at the brink of not being able to handhold? You can increase the ISO. This number designates how sensitive your sensor is to light. This idea is most commonly synonymous with the film that people used to use. ASA 100 or ISO 100 film was for outdoor use with bright and sunny conditions. Whereas ASA 800 or ISO 800 film was for outdoor action or indoor use.
The higher the ISO, the more sensitive your sensor is, which in essence lets more light in. For example, at ISO 100, if I had an exposure that was 1/100th of a second with f/4, to achieve the same exposure at ISO 200, I can go with 1/200th of a second and f/4.
The downside to increasing the sensitivity is noise. Noise, also known as grain, is usually unwanted and can distort the image and render it unusable.
This picture in my opinion is useable. But notice the prominent noise or grain especially of the darker parts of the image. Increasing ISO is a compromise. However, with current technology (such as with the D3S), we are able to shoot in even darker environments with even cleaner results. There’s no doubt in my mind that this technology will improve with time. Back in the days of film, ISO 6400 was unheard of. Current technology breaks the barrier with a maximum of ISO 102,400 with select cameras.
And lastly white balance. This one is fairly easy. Basically, it is just how your camera perceives the color.
Here is the example that we’re going to use. The picture below is the correct white balance. This is exactly what I saw when I took the picture.
And the following picture is the same picture that has an inaccurate white balance. In this following example, it is too “cold”:
And this picture is too “warm”:
When colors need to be accurate such as for product photography, it is important to have the correct white balance. For me personally, I like to have accurate white balance all the time. However, Different effects can be achieved using different white balance settings.
It was around 4PM when I took the picture and it looked exactly like the first picture. Notice how the second picture gives off a feeling of a later time. And notice how the third picture with the warmer white balance achieves a look that suggests a hotter and eariler time.
In essence, the four factors that were discussed are the technical aspects of what make up an image. I hope this helps people understand what each element is.
Don’t hesitate to leave me a message if you’re unsure about anything! And there’s always google!
I hope you enjoyed this post!