Tuesday, June 22, 2010

Photography tips: Aperture and Depth of Field

Firstly I want to thank everyone for the enthusiasm about my photography tips column! I’m half surprised you understood anything I said because I was kind of rambling, but that’s good that you seemed to! Haha!

Okay, so I wasn’t quite sure what to do for this one because when I thought of the photography tips idea I really only had one idea in my head: the last post I did. I had a think about it and tried to think of things that I remember learning when I was first really getting into SLR photography – so I’ve decided to talk about aperture and depth of field.
I know some of you reading this will know all about it and that’s cool, but if there are a few people out there that don’t then I think this might be a revolutionary post for you, haha!

I used to look at pictures where a wide aperture was used and think ‘they’re great photos’ but I’d never know why, then one day I realised that I liked them because the background was blurry – that’s when I began my love of aperture.
To be honest, I know about zilch about the technicalities of photography. I know how to use all the buttons on a camera, but I don’t know anything about what’s going on inside the camera (I guess that’s what you get for being self taught! Actually when I think about it, I’ve never done a proper photography class in my life...)
But what I can tell you, is how it works to change how your photo looks.
So when talking about aperture you have wide aperture or narrow aperture. Funnily enough, a wide aperture is the smaller number and narrow aperture is the bigger number. I’ll try to think of a way you can remember that because it took me about a year. Some people refer to it as large and small aperture, but that just makes it even more confusing. So let’s go with wide and narrow. Actually I remember that when I'm talking to people I often refer to it as wide aperture and 'big number' aperture. Smart, eh? But we'll stay with wide and narrow to try and get you to memerize it!
(Note: when speaking of aperture in numbers, you use an f which means something to do with ‘focal’. E.g. f2.8)

What aperture does is determine the amount of light that is let in when your shutter opens. Wide aperture lets in more light than narrow aperture. What it also does is change the depth of field or depth of focus (same thing, different name).

I’ll use photos to explain depth of field, because it’s just easier that way.

The photo on the left is taken with a wide aperture (f1.8), the photo on the right is taken with a narrow aperture (f8.0). Obviously, the photo is taken focusing on my finger. With a wide aperture, the background is very blurry, with a narrow aperture, it is a lot more in focus!

So that’s pretty much what I’m going to talk about – depth of field! It is a very, very handy thing and for those who aren’t particularly photographically knowledgeable, a depth of field where the background is out more out of focus will instantly be a better photo! (In saying that, for someone who knows loads about photography will probably go ‘er, she’s just using a wide aperture to look good’ but who cares!)

Here’s an example of a portrait with changing apertures. Is it just me, or does the one with the wide aperture look way better? (Okay both pictures are terrible. And I really need to start wearing make up at work.)

 But hopefully you get the general idea. This is a pretty bad example, but the idea is that wide aperture brings the subject forward so that the focus of the photo is on them. When you look at the left photo you probably look at my ridiculous face, when you look at the right photo you're probably like 'What a dou- hey, what's that in the background!'

That’s not always the case, but it can really clean up messy stuff in the background and it makes the subject look extra in focus.

[For those interested, this is in my office at work and I stick photos that have gone in the paper up on the wall if I really like them , to inspire me!]
Okay. So now you know (or have been reminded) what aperture is and how to use depth of field to your advantage. I should point out, however, that there are other things that contribute to depth of field.
- Focal length. You can make your background blurrier depending on your focal length. For example, with a camera with a lens focal length of 50mm and an aperture of f2.8 compared to a camera with a lens focal length of 100mm and f2.8 taking the exact same photos – the 100mm lens will appear to have a blurrier background than the 50mm lens.
- The distance between your subject and their background. The further your subject is away from your background, the blurrier that background is. For example, if you take a picture of someone with a wall directly behind them, the wall will hardly blur out. But if you take a photo of someone with nothing behind them but rolling hillsides in the distance, they’ll just be a big blur.

I hope I’m making sense here!

Here are some extra tips for when you’re playing around with aperture that should be considered.
- If you have a wide aperture and you focus on your subject then the background will be blurry. However, if you focus on your background – your subject will be blurry! It works the same for things in front of your subject and behind your subject. So, for example, if you wake a picture of someone leaning on a fence and you stand right near the fence too, the fence will be blurry until it gets to the subject, where it will be in focus, and then it will blur out again. So be wary of this.
- This is the same for taking a photo of more than one person. If you have a wide aperture, two people, and you’re focusing on one persons face, the other person will probably be out of focus. The only way to get them both in focus would be to make sure they were both in the same ‘line of focus’.
That pretty much means, if you have you camera set up exactly parellel to a line drawn on the ground, and two people stand on that line next to each other - as long as they are both on the line, when you focus on one of them then the other person will be in focus. If one person takes a step back or foward, then they will be out of focus.

- I probably consider everything from f1.4 to f5.6 to be of wide aperture. Lenses have a limit on the wideness that they can go. I have one lense that can go down to f1.4 and one that can only go to f5.6. A narrow aperture is anywhere from f6.3 to f22, but you probably don’t go above f10 unless you’re doing something crazy!


Well hopefully some of this has helped you and it actually made some sense. 
As always, if you want to know something about photography then just reply here or email me at grace.johns@gmail.com and I can write up a post about it!
Similarly, if you have any questions about this post, feel free to do the same thing.


Ms. Chyme said...

Great post. Thanks a lot for sharing these ideas.

Teresa said...

I've been meaning to get an SLR camera to take better photos but your tips will definitely come in very handy when I do! Hopefully sooner rather than later. :)

Hannah said...

Just skimming through this gave me lots of info that I didn't know before. I'm going to have to come back and read this in more detail when I've got more time. You're totally making sense, even for a supreme beginniner such as myself. Your tips seem ver helpful indeed.