Tip #5 - Using Aperture Priority

I'd say, given the nature of what I do as a photographer, that probably 95% of the time, I have my camera set to Aperture Priority. Aperture Priority is the AV (Canon) or A (Nikon) on your camera.

As I have mentioned before, photography is all about light. Effectively your aperture is how wide the opening is to the camera's sensor, and therefore controls how much light is hitting the sensor (along with, obviously, the speed of the shutter as discussed in last weeks tip). Apertures are expressed in f-stops (said just like it's written... it is not short for "full stops!). I'm not going to explain f-stops and how they work... it's really quite technical.

Again, remember this simple little rule:

The WIDER the aperture = the "smaller" the "number" (f-stop) = the shallower the depth of field (the less in focus) = the faster the shutter speed.

Ok, so you're saying... so what? What does that MEAN for me, and why would it matter? As I have mentioned before, sometimes you want to control how much is or is not in focus. As a portraiture photographer, I often like to blow out the background.. I particularly love lots of bokeh.. oh, beautiful, beautiful bokeh! And what about that wedding photograph of the bride in focus, and the groom a few paces behind NOT in focus... or the other way around? That, my friends, is controlling the aperture.

But, it gets better.

Look at the line above (have you memorised it yet?): aperture and shutter speed, as you know, are related. Perhaps you have a fast moving toddler? You need to up your speed, right? Well, widen up your aperture, people. Set your aperture to f5.6 (or higher), and your speed will be faster than at say, f11. What does this do? Well, if your speed is fast enough, you'll freeze motion. Sure, you're gonna have to remember where your focus is.... because again, if you're widening your aperture, to increase your speed, there's a chance, if you're not careful, that you're going to focus on the wrong thing. But swapping between modes constantly- well, not always practical, particularly if you're chasing after a fast moving toddler. So 95% of the time, I keep it on one mode, and adjust the aperture based on how much detail I want in focus, what the light is doing, and the speed at which my subject is moving.

Effectively, what using aperture priority will do, is when you widen the aperture, you allow more light in, meaning that the speed at which your shutter opens and closes will increase. Likewise, when you "stop down" to a smaller aperture, this allows less light, which will in turn slow down the shutter speed.

But likewise there are times you HAVE to have more in focus. If, for example, you have a large group of people, and they're all at varying distances from you. If you set your aperture really wide open, you're not going to get all of them in focus. Great, if you're going for that look. Not great if Granny wants a picture of all her grand kids on her wall, in a group... she's not looking for your creative genius, she's looking for all of her grand kids to be in focus, so that she can ooh and aah at her great gene pool.

But it's more than just speed and focus. For example, on a really bright sunny day, on a wide aperture, you could overexpose your image (that's the nasty bright white image). Stop down a bit to a smaller aperture. This will allow less light, equating to a better exposed image.

So try this example:

1. Line up all your kids about a metre apart, one behind the other. Take a photo down the line (so all kids are in the picture), first with a really wide open aperture (say f5.6, or f2.2 if you have a lens that is really wide open); then secondly with a small aperture of say f16. Be warned, for the second you'll need a tripod. If your kids won't stand still, try the same example using chairs.
2. On a bright sunny day, at the beach, take a picture at the widest aperture you can, of a bright subject, like your child. Blow outs? Stop down the aperture only, and see at one point there are no longer blow outs, and your picture is correctly exposed.

When you're taking pictures, watch what the speed is doing in relation to the aperture, and visa versa. You see, it's not enough to simply SNAP AWAY. A hit and miss scenario is never going to make you a better photographer... it just makes you lucky when you get a great shot.

This takes time, and it takes practice. And be warned: you're going to get worse before you get better. But in the end, it will be worth it!