This post will be part of a three part series looking into the basics of operating your cameras full manual mode. Aimed at complete beginners, these posts will be teaching about the three main functions. Aperture, ISO an Shutter Speed. In this post, we will be looking at Aperture.

What Exactly is the Aperture?

Aperture (Also known as the F-Stop) Is the part of the trio that most people struggle with. But it needn’t be so! I am going to try to aim this post towards the absolute beginner explaining things in a most simple way.

Bokeh blurry background - f/1.8

I took a photo of a cake, hmmmm. Aperture set at f/1.8 to give a nice blurry background. (Bokeh)

The aperture is the hole inside the lens which light passes through to reach the sensor. I want you to Imagine your eye is a camera lens for a moment. When you walk into a dark room, your pupil automatically widens to allow more light onto your retina. This would be the equivalent of your eye increasing its aperture. When you step outside on a sunny day, your pupil will reduce the amount of light allowed into your eye by making the opening of the pupil smaller. The lens of your camera imitates these actions – the aperture.

The aperture has a second and more creative purpose. Have you ever seen photos where the depth of field is really shallow, where the subject is perfectly in focus but the surrounding background is blurry? You can create this effect by correctly controlling your aperture settings. The wider the aperture, the more blurry the background will be. (Also known as Bokeh)

Now, before we go any further, I am going to get a little deeper – and slowly break it down technically because this is the part where people get confused. Well, I did anyway!

The smaller the f-stop number is, the wider the aperture.

I found this part the hardest  to get my head around when I first started learning photography. The smaller the f-stop number, the wider the aperture. For example, If you have your aperture set at f/1.8, you will be letting in a considerably lot more light than if your setting was at  f/22.

Lens iris and f-number relationship

Image courtesy of Wikipedia, demonstrates the relationship between size of lens’ iris and f-number.

In fact, if you were taking a standard photograph and your aperture was set at f/22, the chances are your image will be completely black. When reading specs on lenses, you will see something like, “Maximum Aperture f/1.8, Minimum Aperture f/22.” In a numerological sense, It is completely opposite to how you would logically expect! So bear that in mind!

The smaller the f-stop number is, the shallower the depth of field will be. (Blurrier the background will be)

‘Depth of Field’ (Sometimes written just as DOF) literally, is just how far (or deep) the focus extends behind the subject being focused on.

f/1.8 v f10

Image on the left was taken at f/1.8 while the image on the right was taken at f/10

So, imagine you have some wine glasses arranged on a table in front of you. (Or just take look at the image to the left) Now, as you would normally do when taking a photo of a group, focus your camera on the first glass. Once you take the photo, how focused the glass behind will be will depend on what you have your aperture set at. If you had your aperture set at f/1.8, because the depth of field is so shallow, it is likely that the very first glass will be nice and clear but the glass behind will be blurry. Changing your aperture to f/10 will deepen the depth of field so that the glass behind will be sharper. How sharp will depend on how close behind the front glass it is.

Relationship between the depth of field the and brightness.

In my early days I found putting the above lessons into practice very challenging. I could never remember which direction to adjust my aperture in order to get the correct balance of lighting and or depth of field. (Shutter speed and ISO also come into play, but for now, we are just focusing on Aperture) Once I taught myself the following quite unconventional way of remembering it, it all fell into place and stuck there until remembering it came natural. I will now share this method with you.

I am going to use the behaviour of light within in a swimming pool as an analogy to demonstrate how I remembered the link between f-stop number and light/bokeh. It is very important that you understand that this is JUST an analogy and that the numbers and figures used below are NOT to scale in any way.

Aperture to f/1.8

Low F-number  = lighter pictures and shallower depths of field.

f/1.8 for brighter photo

Main focus is on the man. f/1.8 opens this particular lens to its max aperture allowing for maximum use of the natural lighting without flash.

I want you to imagine a swimming pool with a thin 1.8cm strip of water covering the bottom. Anything completely submerged in the water will be in focus. Note – not only is the water very shallow, (photo – shallow depth of field) but there is also plenty of light within the water as it isn’t very deep.


Aperture to f/10

Higher F-number = Darker photo and deeper depth of field.

Now, we have raised the depth of ‘water’ to 10cm. (once again, f/10 does NOT mean 8cm, this is just an analogy) Everything covered by the water is in focus. The depth of field is deeper. But as it is deeper, it will now be slightly darker because there is more water for the light to fill.

And so it stuck in my mind by remembering these examples! I no longer thing of the relationships like this, but it helped me in the beginning and maybe it can help you too.

Wedding Photo f/10

Photo taken at f/10. Entire group is in focus.

As mentioned above, when we decrease the size of the aperture (make the f-number larger) the photo will become darker.  In a later lesson I will cover the working relationship of ISO, Aperture and Shutter Speed so that we can counteract these effects to create your exact desired effect.

I hope you have found this very elementary lesson helpful. If there is anything you don’t understand, don’t hesitate to comment/ask.

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