In this episode I'll be explaining
how the aperture controls depth of field.
AdoramaTV presents, Exploring Photography with Mark Wallace.
Hi everybody, welcome to this episode of
Exploring Photography right here on
AdoramaTV, it's brought you by Adorama it's the camera store that has
everything for photographers,
make sure you check them out at Adorama.com. Well here on Exploring
Photography I have been talking about the exposure triangle
and we talk about the aperture, the shutter
and the ISO, what those three things to do and how they're related in stops and things
like that. I've been saying that the aperture controls depth of field
but what is that? Well on this episode we're going to explain exactly
what dept the field is and to do that I've invited
Lex to come and be our model. Here we are in beautiful Hyde Park, Sydney
Australia, in downtown Sydney Australia we've been having a blast here.
Well to understand how the aperture affects depth of field we first need to understand
what depth of field is,
and when we focus our camera, Lex just look right at me here,
when we focus our camera, I'm focusing from my camera
to a specific point so it's a distance, so this is way too close but
let's pretend I'm focusing right here.
So I'm focusing from here to here that might be a foot, that might be two feet,
it might be six feet
but we have to understand that we're focusing to a distance. Now the other thing that
we're doing is we're not just focusing to a distance, we're focusing to a depth.
So how much have Lex's head to I want in focus and how much of the background? So
to understand that a little bit better, Lex I'll have you go back here about six feet
away from me
so if I'm focusing at my focus point about six feet away from right here,
I'm going to focus on Lex, I'm also getting a bunch of stuff behind her in focus
and in front of her
in focus and how much of that we get is called our
depth of field. So shallow depth of field, not very much in focus except for
our subjects extreme field of sharpness,
thank you Tamara Lackey for letting me steal that from you, that is when we have
everything in focus.
When we have an aperture value that is
a high number, a small opening like f/16 or f/22,
we have everything in focus, but when we have our aperture value,
a really small number like f/2.8 that's a really
large opening and not much is in focus.
So let me show you exactly what I mean now we have a horrible setup right here,
we're in Hyde Park in Sydney Australia which is a beautiful park
there's a lot of people around and to illustrate this I've set this up where we have a bunch of
trees behind Lex's head,
we intentionally set this up in a bad scenario to show you the
benefits of shallow depth of field. So if I shoot at around f/16
I'm going to have almost everything in focus. So Lex, let me make sure I focus right
here on your
eyes, beautiful. Alright let me make sure my camera is turned
on, excellent. Alright so what we're going to do at f/16
is I'm going to get a shot here and we'll see clearly
that we have big problems, we had Lex and we have this big tree growing out in the back
of her head.
Now I can move around just a little bit and try to make this a little bit better
what the problem is, the background is just
it's all over the place. What I want to do is get shallow depth of field to clean up
that background,
portrait photographers love. So I'm going to go all the way down
and I'm changing my aperture value from f/16, all the way down to f/2.8
so I'm opening it up.
So now I'm going to focus my camera on your eyes one more time and I make sure that it is
perfectly in focus, yes there we go. Alright, now
let's take that exact same photo, perfect,
and you can see that those trees are falling into focus,
it's cleaning things up. Well this lens goes all the way to f/1.4, it's got a huge
aperture opening and so we'll do this one more time
and you can see that I can really cheat this, I've got to make sure I'm in focus
here before I shoot this picture
there we go. Now I'll take this last picture.
I like that so much more, Lex come up here and look at this.
Now one of the things that you have to note is when you're shooting with a
really wide aperture, like f/2.8 or f/1.4,
you have to be really
careful on your focusing that's why I was being really specific on that
because just any camera movement can knock your focus out, so you might have the
subjects hair in focus but the eyes
out of focus, or their nose in focus and their eye is out of focus, it can be that shallow.
We can take a look here and here's this very, very first picture that we took
and you can see that we've got stuff growing out of your head that's just no
good, that was at f/16. Then we went to, we recomposed, we shot, not so good
we went to f/2.8 that looks so much better and then
all the way down to f/1.2 and that's the winning shot where we've got the
background that's
totally falling out and you can see the difference between f/16
f/1.2 it is much, much nicer. Now one of the
disadvantages or advantages, however way you want to look at it.
Most lenses don't have a f/1.4
aperture value this is a fancy lens and you're going to be stuck at f/5.6 or f/2.8 or
something around that
so what can you do? Well the good news it's just not
only the aperture that determines depth of field but the size of your lens, the
focal length: and how close you are to your subject. So can you get that really nice
out-of-focus bokeh background with a lens that doesn't have f/2.8?
Absolutely. You want to be shooting with a 200 or 300mm lens
or maybe a 150mm, 135mm something like that. You don't want to
shoot with a wide angle lens because the wide angle lens is going to have
everything in focus almost
every single time, and to prove it to you I'm going to show you two pictures that we took
just a few minutes ago. One; this shot right here was shot with the
135mm lens and we did this at an aperture value
I believe, about f/5.6 or 8, around there and you can see
that we have a really nice shallow depth of field.
Now this next shot we shot the exact same thing but we used a wide angle lens
take a look at that. Now this is a 21mm lens, oh my gosh
everything is in focus from start to finish even when we go to the widest
aperture value
you can see that we open our aperture wide open but everything is still in focus so
the size of your lens really
matters and the other thing that matters is how close you are to your subject, so
the closer you get the shallower your depth of field is going to
be, the more
out-of-focus the background is going to be, and the farther away you get
the more you're going to have everything in focus, so do you want to get your really
nice shallow depth of field
use the longest lens you can and get as close as you can
with the widest aperture that you can possibly have and you'll have a winning shot.
Well there you have it, the aperture
depth of field an our exposure triangle when we're trying to figure out
do I start with the aperture or the shutter speed, well if you want depth of field
the aperture is a huge, huge contender
and now you know why. Well thank you so much for joining us for this episode of
Exploring Photography and don't forget
that the Adorama Learning Center has tons of information about depth of field
and focusing on all the stuff we talked about today, in fact
about five years ago I did an episode on depth of field
and I looked at it before making this episode, it's sort of dated but it's still there on the Adorama
Learning Center, it's absolutely free so check that out
and don't forget that you can subscribe to AdoramaTV it's
also free and you won't miss a single episode. Thanks again for joining us and
we'll see you again next time!
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