Friday, 6 May 2011

It's All Av, Baby

Hold me.

No, not Alternative Vote - I'm going to talk to you about the meaning of aperture as I know it. I use a Canon EOS 500D. It's still my baby and I love it.

When learning how to use a DSLR I was so confused at the meaning of aperture and shutter speed that I just messed about with the settings. I thought it controlled how bright or dark a photo was. And in a way, I was right.

For a while, well, since October until about the start of April I had my camera set in Creative Auto only. For people who are just starting out this is a really good way to begin learning. On the Creative Auto screen you could control how blurred or sharp the photo was, the flash (on/off/auto) and how light or dark the photo appeared.

After a while I felt really lazy. I felt like although the Creative Auto function did an awful lot for making pictures look gorgeous, I wanted to take it to the next level. And after acquiring a 50mm lens you do want to achieve the bokeh effect (bokeh - when you take a photo, and the subject is all in focus but the background around it isn't - it's all blurry and light particles appear as dots. Some clever folk, me included, have worked out how to change these dots to hearts or stars etc. This is one for another blog post) and that's something you can only do by playing with the aperture. So I switched to the Av function and haven't looked back since. Av = Aperture priority.

I had no idea what aperture meant. And after reading on the internet and borrowing basic DSLR photography books I was still confused.

I learn by doing (hence why I like to read and then try things out and cry and swear if when I try a written tutorial online I get confused. I learn by doing so if someone shows me and gives me a written explanation or I make notes I'll be fine) so the only thing I could do was to play with the camera and see how I got on (any excuse!!!).

Aperature is measured in F stops, for example F/1.4, F/3.2, F/8.0 - your lens and the camera dictates how big the F stops go up to, and how small.

Now here's the confusing part for me.

F/1.4, when it comes to looking at numbers in a mathematical kind of way, means the smallest number, right?

And what about F/8.0 - that's a huge number, isn't it?

Wrong, actually.

The numbers actually refer to how wide the aperture (that's the little round circular shutter on your lens) is open. So, for example, if you have set your camera on Av to F/1.8 the camera will focus in on the subject closest to it, and only that, and be damned anything else that's hanging around in the picture, it only cares about the subject you're pointing at and the subject only.


I like this one, although it was a total accident. I was meaning to focus on the sunbathing couple (who were, I admit, pretty chilled out and quite a way away from me hence making it easier to take the photo) but instead got the grass. Can you see how the grass in the foreground is nice and focused, and the sunbathing couple, the sea wall and the sea itself are happily blurry? That's the effect of a very wide aperture. I keep going to type that it's very tight, but I am wrong. I am so wrong.

You could keep shooting at F/1.8 for a very long time although it could make group shots tricky. You definitely don't want to leave Great Auntie Deirdre's face out of focus! In order to include more in the photo, you need to turn that dial up.

Red & Blue

Like anything in life, you'll find you have a favourite, especially when it comes to F stops. Mine is F/3.2 - this is fabulous because it opens the lens wide enough to focus on a lot of the subject, but still leave a lovely bokeh effect in the background.

Very bunny

This was taken on F/4.0 so I could capture all those lovely chocolate bunnies. In fact, where are they now? (answer - in my tummy)

In short, the higher you go, the smaller the aperture. Like this, shot on F/11:

World's Best Water

The water, the sea wall and the shoe in the background are happily in the foreground. The higher you go, the more that's in focus.

So, let's just go through this all again:

F/1.4 is a large number. It means that the aperture is huge, and whatever your subject matter is, they will only be in focus.

F/11 and above is a small number. It means everything will equally be in focus.

Just think in reverse (if you can!) and you will slowly get to grips with it.

This is how I see it, anyway.

And aperture priority, before I forget, is the option on your camera which lets you control the aperture on your camera only. The camera takes care of everything else like ISO (if you set it to auto) and shutter speed. But you can adjust what the sensor picks up.

For example if your little cousin is eating an ice cream on the right hand side of the viewfinder and you want to take a pic while he's not looking, there will be a button which lets you set it so that he's not out of focus. On a Canon it looks like a little box with several dots arranged in a cross shape. Press it, and then you can choose where you want to set the sensor to focus with the dial you use to adjust your aperture. Easy, huh? Just make sure you set it back when you go to take a photo of something else, or it might not focus right.


Like this.

So, I hope this helps everyone. I know it might not all be technically correct but it's probably the easiest way I could explain it - and if it helps someone it's a bonus. When I learn more you'll be the first to know.


  1. I love, love, love a low f-stop (as you may have noticed) I always have my canon in AV - but I tend to set everything else as well. Aren't they just the most amazing things to play with? Am looking forward to learning how to do shaped bokeh :)

  2. Awww, thanks my lovely! I love aperature priority - I finally feel like i'm learning with the camera! Heart bokeh is so easy to make, I can't wait to do the tutorial on it.


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