SLR photography — a beginners’ guide

As prices of digital SLR cameras come down, more people are buying them. Perhaps you’ve been inspired by your compact digital camera and want to take things to the next level. So you bring home that fancy new toy with the interchangeable lenses and a manual that tells you everything except how to actually use it, and you realise things are complicated. Crazy complicated. Where do you start?

There’s a lot of good stuff about photography on the internet, but much of it is technical and assumes you already know photography theory. This plain-language guide is for the rest of you.

Before you start

First thing I’d do is get one of those UV filters to screw onto the end of your lens. A UV filter doesn’t do much — well, I guess it filters UV — but I personally use them because they offer a little bit of protection for my lenses. If your lens gets bumped, scratched or dirty then you’ll be glad that replaceable filter took the punishment instead of your expensive lens. Of course there’s a limit to how much protection a lens filter can provide, but at least it’s something.

Once it’s attached you can leave it on. Your lens cap should clip right over the top of it when the camera’s not in use.

Fully Auto

Yes, there’s that fully-auto setting which turns your SLR into an aim-and-shoot box. I bet the salesman in the shop pointed that feature out to you. In a hurry? Then select Auto, and shoot. You’ll get a lot of good photos just using that setting. But one day you’ll realise you’re missing out on some of the best fun, and best shots too. Because Auto tries to guess what you want, and even the smartest cameras don’t get it right all the time.

Multiple focal points

We’ll start here because this bit can cause a huge amount of frustration right at the beginning with a new SLR. Modern SLRs often use a whole bunch of auto-focus points to help you take better pics. That is, when they’re not making you take worse ones.

Here’s an example. See that blurred thing in the picture below? That’s supposed to be a wren. But the wrong parts of the image are in focus. This can happen a lot when you have all focal points activated. And it makes sense when you think about it — all those focus points are much more likely to latch onto one of those many bits of foliage instead of that one bit of bird.

That’s why one of the first things I do is choose which focus point I’m going to use. I select it and then the camera remembers my choice until I change it again. Now, to select a focus point will probably mean you need to work in something other than fully-Auto mode. Because we’re only learning here, then Aperture Priority mode (AV) should do fine. You can set your Aperture to f/8 for example, and then choose which focus point to use (you might need to check your camera’s manual to find out how to select focus points)

So which focus point do I use? Most of the time (but not always) I use the centre one only. That means the camera will focus on whatever’s in the middle of the frame as I press the shutter button. As you get more comfortable with your camera and composing your shots, you might find situations where some other focus point, or all of them, is a better option. But the important thing is that you decide, not the camera.

There’s another nice feature about selecting which focus point you want — you can focus your shot by pressing your shutter button half-way down and then keeping your finger on the button, you can then re-compose your shot. The focus gets locked in because you’re keeping your finger held down, even while your recomposition of the shot means the bit in focus is not in the middle of the frame any more. Press the shutter button the rest of the way down to get your shot. (Note that this trick won’t work in servo-focus mode because servo-focus is focusing continuously and therefore refuses to lock.)

And now we get to what I think is the core of SLR photography:

Depth of field, f/stops and shutter speed

Why am I lumping all these things together? Because they’re all connected.

When you understand this bit then the rest of photography, especially the bits which make SLRs such great cameras, will start making a lot more sense.

I’ll start with Depth of Field

Depth of Field is a term photographers use to describe the amount of distance between the closest and farthest objects in focus. So, imagine you want to photograph a landscape and you’d like everything from the shrubs up close to the remotely-distant hills on the horizon, to all be in sharp focus. What you are asking for is lots of Depth of Field (DOF).

And there will be other times when the background will be just too much of a mess and you’d prefer to blur it away, like in the Kookaburra photo above. Well, your clever new SLR gives you that option too. Some of the better compact digital cameras can do this, but not as well as a digital SLR. The reason is a bit tricky to explain but for now you can be happy to know that it involves the larger sensor used in digital SLRs.

So then, how do you do it?

Easy! To get lots of Depth of Field you go to AV mode (Aperture Value priority) and choose a big f/stop number.

Now it’s important I go off on a bit of a tangent here so you’ll understand what I just said. A big f/stop number means you are closing down the hole in your lens — the hole letting the light into your camera — into a small opening (see the pics below). And a small f/stop number creates a big opening.

Why does the big number equal the small hole and vice versa?

The answer is, because the f/stop number is a fraction. It’s like how 1/100 is a smaller amount than 1/5. That's why f/22 creates a smaller hole than f/2.8.

Here’s what you need to know: The bigger the f/stop number, the smaller the hole letting light into the lens, and that gives you more Depth of Field.

And of course, the opposite rule applies. If the light enters your lens through a big hole (small f/stop number) you get less Depth of Field. Which means your subject is in focus but other bits can be blurred. That kind of effect can be especially effective (and flattering) when taking portraits, and it also gives a very pleasing effect of matching the way a human eye works.

Okay, you’ve survived one half of the equation and most of the brain work. Now for the other half.

It all comes together

We’ll use the f/22 example here. You chose that tiny Aperture because you wanted to get lots of Depth of Field. Because you’re letting light into your lens through a small opening, there’s not much light reaching your camera’s sensor/film. It’s like being in a house with the blinds mostly closed. So your pics will come out too dark (underexposed). To make up for that, the camera’s going to want to brighten things back up again by giving the exposure more time. It does that by slowing down the Shutter Speed. Which is why Depth of field, Aperture and Shutter Speed are all connected.

Have a look at the diagram below to see a rough guide to this whole thing.

Photography becomes a balancing act between Depth of Field, Aperture and Shutter Speed, with you, the photographer choosing which aspect to give the most priority to, according to what you’re photographing at the time and how you think it will look best.

So, if your main concern is controlling Depth of Field, then you give priority to your Aperture setting, because that’s the bit that controls Depth of Field. You choose Aperture Value Priority mode (AV mode) and select the best f/stop for the amount of Depth of Field you want. Your camera will then work to get the exposure right by choosing the right shutter speed for it.

Likewise, if your main priority is the exposure speed, (like if you were photographing fast-moving subjects) then you go to Time Value Priority mode (TV mode), choose the appropriate shutter speed, and your camera will select the right Aperture setting for you.

I think it’s time to throw in one of photography’s rules because you’re ready for it now: Whenever you half the size of your aperture hole you have to double the exposure time. And vice versa.

Is there anything being left out here?

Yes, of course there is.

Imagine you want to take a photo of a fast-moving critter hopping around in the weak light just after sunrise.

So you choose a fast shutter speed, like 1,000th second, to freeze the action.

At 1,000th of a second your camera might not have enough time to capture enough photons of that weak early-morning light. Wouldn’t it be nice if you could somehow make your camera more sensitive, so that it does its job with less light?

Well you can.

Back in the old film days, we used fast film for low-light situations. The same rules apply with digital.

By increasing your camera’s ISO setting you will increase the sensitivity of your sensor. Which means suddenly your camera is getting enough light again.

I haven’t discussed ISO until now because I figured you had enough to think about, and I won’t say too much more about it right now for the same reason. But here are a few things about ISO:

1 - By default, your camera should be taking care of its ISO settings automatically

2 - Increasing your ISO settings will allow high shutter speeds, or small apertures, in less light

3 - The down side of high ISO settings is that they tend to create more noise in your pictures. By that, I mean that the photos tend to be speckled with incorrectly-tinted pixels, especially in the shadow areas where the poor light issue is at its worst. Still, you might find that you can take your camera’s ISO settings up a bit without too much loss of image quality, and the pros often do exactly that.

All the other rules still apply, but just understand for now that higher ISO allows you to work in weaker light.

To learn how to crank up your ISO you might need to glance at your camera’s manual. But you must be wary of maxing out your ISO settings, or else you might get some unusable images.

There are lots of variables in photography and I could go on and on about them. For example, a telephoto lens (one with a very long focal length) will give a smaller Depth of Field than a wide angle lens at the same f/stop. But the same general rules about Depth of Field, Aperture and Shutter Speed apply.

What next?

So you’ve made it through the basic concepts behind camera exposure. How you apply this is the trick behind using your SLR camera and that is surprisingly straightforward. I want you to be nice and clear about what we’ve already learned. It’s at the heart of knowing when to choose things like Aperture Value Priority (AV) mode or Time Value Priority (TV) mode as you step outside to take your shots.

And the easiest way to make sense of it all and help you remember it, is by talking about some different situations out in the real world. You’ll see how we’re using this stuff to make decisions which drive your SLR camera towards much better photography.

Beginners’ series on
digital SLR photography

• A beginners’ guide — basics for digital SLRs
• Learning from examples — picking up where the first article left off
• Understanding histograms — making sense of this handy tool
• Preventing washed-out photos — why it happens, and how to prevent it
• Understanding Exposure Compensation — why your photo subject can look so badly exposed, and what to do about it
• Megapixels — how many is enough?

Photo Sales

• Photo Library — pics of Australian critters

An unhelpful guide

• Wildlife photography — this guide will not make you into a better photographer
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