What (the fuck) is Aperture all about?

I've been meaning to write this for a long time, as it took me long enough to get motivated to find out! If you search around there are some really good articles on the subject, but it's a whole heap of stuff that can get quite confusing if not explained concisely - and also there waaaay too much information for the fumbling amateur like me. It just freaks me out. So, what the fuck is aperture? Basically, the size of the hole the light comes through!

So let's take a quick look at the setting on the camera. Really simple, it has a little 'Av' icon - you can see it pretty clearly in the photo. Select this and you'll be able to adjust the size of the aperture.

• The smaller the number, the larger the aperture.
• The larger the number, the smaller the aperture.

Easy, right? But what does that mean exactly? Well, this is probably not exactly correct, but whatever, I'm not a scientist, so this is works for me!

A large aperture (That's a low number, remember?) lets lots of light in, so you can get away with a quicker shutter speed. A very small aperture (Big numbers!!) means you'll need to keep the shutter open for longer to make up for the smaller opening. Make sense so far?

So what's the big deal? What does it all mean? This is where it gets really interesting... The size of the aperture affects the depth of focus. Read that sentence again - it's super important here.

Why don't we look at what that means in real life. I've set the camera to Av mode as mentioned above, ISO100, no flash with my awesome 50mm f1.8 Canon lens. I spaced the bottles 10cm apart so you can understand better the following effect, and focused on the middle of the five bottles!

f/22 example

Let's shift the aperture as small as possible (small aperture = large number) - we'll take it all the way to f/22 by using the little scroll wheel on the front of the camera. As I half-pressed the shutter release button, the camera tells me I'll need an 8 second exposure (shutter speed) to allow the right amount of light in through the tiny aperture. The Av setting leaves the shutter speed totally automatic, so no need to worry about that here.

f/1.8 example

Now... Let's open the aperture right up (large aperture, small number) - this lens goes all the way down to f1.8 using the scroll wheel. With all of this light coming through, the shutter speed can be much, much faster - 1/20th of a second. NOTHING ELSE CHANGED. I just made the aperture larger! It's amazing how much this small, usually ignored setting can change the whole focus and feel of the photograph.

So this was explained so well in an article I read, I wish I could remember where as I would put the link up here. It made the comparison between f number, and depth of focus. The smaller the f number, the smaller the depth of focus. The larger the f number, the larger the depth of focus. As you can see above, f22 = nearly everything in focus, while the f1.8 = very, very little in focus.

That's it from me, hope this opens your eyes as much as it did mine once I understood. Get out there, take some photos, play, practice, have fun with it. I certainly am!