KRISTEN: So our next keynote
speaker is Alex Lorman.
He is an engineer,
but he has also
been a professional
photographer.
And he's going to tell you
what's inside the camera,
and all the physics behind
it, and some cool things
cool he's done with
his own cameras.
So I'm going to
turn it off to Alex.
Thank you.
ALEX LORMAN: I promise to bore
you all to death with physics.
It will be great, I promise.
So like Kristen mentioned, I
currently work as an engineer.
I build robotic boats right
now, which is all kinds of fun.
But I used to build cameras and
take pictures in a former life.
It's OK, you guys can all
have two careers, too.
This is what I do.
I play with sunken ships,
and now I build them.
It's great.
It's good times.
So also for cameras, helicopters
are really useful if you ever
want to take cool pictures.
You should go out and
ask your parents for one.
So this is actually a camera
I built. And that shot--
the picture on the left--
and before you all say,
no, you didn't possibly
shoot that picture-- I did,
and I can show you
the raw feed from it.
So it's actually a really
old style of camera
that used to use film.
How many of you actually
loaded a film camera.
Awesome.
Wow.
That's actually more than
I would have expected.
So film is the thing,
we'll get into that
in a couple of slides.
This was a digital
film hybrid camera.
So actually the whole
front unit is a film camera
and it had a platen
glass, which is what you
used to use to focus the image.
So before auto-focus
and before fixed focus,
you actually had to focus
a picture, which involved
moving pieces of glass around.
It was super fun.
And then the thing at the
rear takes a picture of that.
So it's a really weird set
up, but it also worked,
and I made it in my basement.
So you guys can, too.
Honestly, it's kind of fun to
go to a camera store, or eBay,
or Amazon, or wherever, and pick
up old used large format camera
gear.
And you can do some
fun stuff with it.
So this did shoot the
image on the left.
You see it has a really sort
of odd, dreamy quality to it.
That was in 2008.
But it can do some
interesting stuff.
Most of the Secret Service
will think you have a bomb.
But that's OK.
So I've built some
other cameras as well.
You can build time
lapse cameras.
This is taking apart go pros
and soldering things onto them
so that microcontrollers--
similar to the Raspberry
Pi's-- actually, a lot simpler
than the Raspberry Pi's-- could
control them and take
a picture every--
I think this was taking a
picture every half an hour,
something like that.
So it actually turned the
GoPro on, take a picture,
and then turn it off again.
And you guys are actually
building something much more
sophisticated than that,
so if you guys can all
do your stuff today,
you're way ahead
of where I was a
couple years ago.
It'll be great.
So that was also solar powered.
That was fun.
That was-- why is my
clicker not working?
There we go.
So this shot this.
It will give you a
minute of time lapse.
That stayed on the top of
a mountain on a project
I was working on for-- it stayed
up there for like six or eight
weeks or something.
I only give you a minute of it.
It worked out pretty well.
It was a fun little project.
Time lapses are cool when
they actually show something.
In this case, they're not
actually showing very much.
So there's one or two cool shots
where you get a nice sunrise.
There we go.
Isn't that pretty?
All right, we won't bore you
with any further details.
So, cameras and how
they've developed.
I'm sure there are
further notes on this,
and this is not an exhaustive
history of cameras,
so don't quote me on any of it.
In fact, I might
even be making it up.
I probably am.
Apparently in 1839,
photographs were
on paper that probably had
something to do with chemicals
that reacted to light.
I'm just guessing.
But in 1861 they seem to
have gotten it in color.
Now the thing with both
color, digital cameras,
and film cameras,
is suddenly you
need to capture three
different sets of light.
And that's much more key
with digital cameras--
and you'll see that-- you
need to capture red, green,
and blue to make color.
So then apparently in 1884
they made photographic film.
They seemed to have had a pretty
good run of that for about
the next 125 years, 150 years.
And in 1936 SLRs.
We'll get into exactly what
SLRs do, and how, and why,
in just a second.
That's OK.
Instant photography.
Has anyone actually
shot a Polaroid camera,
where you've got like a little
thing that you have to shake?
One.
Cool.
OK.
Polaroid used to be
a lot more popular.
Remember I was talking about
large format cameras before?
You used to check how they
shot by shooting a Polaroid,
and then waiting for
the Polaroid of develop,
and then putting the proper
large format film-- which
was about this big-- into it.
So your subjects couldn't
really be going anywhere fast.
So instant photography
was a thing.
A little bit before my time,
but it definitely was a thing.
I've heard about it.
Auto-focus, we'll get
into auto-focus as well.
People used to actually have to
manually focus their cameras.
They had all kinds
of cool things called
split screens, where
you could-- the image
would suddenly snap into
focus when you had it right.
Those were fun.
You can actually get them for
modern cameras if you want.
Kodak digital camera.
So they basically took a--
I think it was an Icon F5--
and just stripped
the entire thing out
and put electronics in it.
They were horribly,
staggeringly expensive, slow,
and didn't work all that well.
And really the only people
who used them were newspaper
photographers because they
needed to get their images out
as fast as possible.
They were also about-- the first
ones were like one megapixel,
maybe not even that.
They were horrible.
And that continued for a while,
until 1998 with modern DSLRs.
Modern DSLRs are really
amazing, and what
you can get for a couple
of hundred dollars
is unbelievable.
So, a 2012 is the
gigapixel camera.
Apparently-- I'm told--
that is a camera that
has like 92 lenses that
all shoot at the same time
and creates a gigapixel image.
If any of you can tell me
what a gigapixel image is,
that would be great.
Because I don't know.
But I can tell you about DSLRs.
So-- even have a few here.
This looks pretty
familiar to everyone?
Cool.
Great.
Ahead of the curve so far.
This bit, too?
Lenses?
Great.
Let's see if they'll
actually a couple together.
So, yes?
Still with me so far?
And the make clicking noises?
Fabulous.
So in this wonderful
diagram, which
I stole from the internet,
the light path goes in
and we get lens elements.
So if you see
through lenses, they
have bits of glass in them.
We'll get into much more
about how they work.
And I'm probably making
half of that up, anyway.
It might just be black
magic coming through.
It's fine.
It's not a problem.
The aperture.
So I'll pass around a
manual lens for you,
and you can see what
the aperture is.
Who can actually-- oh, come on.
Lord.
Who can actually tell
me what an aperture is?
Anybody?
Yes, please fire away.
AUDIENCE: [INAUDIBLE] small
hole that lets light in.
ALEX LORMAN: Yes.
That is an accurate summary.
So-- here, I'll
pass this around.
The aperture ring
is on the front.
You hear it click.
Look through the lens,
you'll see it change.
Please pass it around.
Just don't lose it.
Awesome.
So she's exactly right.
The aperture controls how
much light is coming through.
You say, why on
earth would you want
less light to come through?
Can anybody tell me?
Please, the back.
AUDIENCE: [INAUDIBLE] picture
doesn't get overexposed.
ALEX LORMAN: Good.
Why wouldn't I just want an
obscenely fast shutter speed
instead?
It would freeze everything
nice and you could get
exactly the right freeze frame.
Anybody else?
It is-- you're right, you
have a correct answer, though.
Please.
AUDIENCE: [INAUDIBLE]
ALEX LORMAN: That's true.
The other one is depth of field.
So if I'm shooting
with that wide open--
and you can sort of see it when
you look through the camera--
you get a really
shallow focus point.
And that's great if you're
shooting romantic portraits.
But if you're not,
you can actually
stop it down-- make it
smaller-- and your focus
area will increase.
So suddenly I'll get the
first three rows of you guys
in focus instead of just one.
So apertures are
really important.
Then it comes in, and
bounces up, and then
bounces around five
times, and out.
Anybody have a reason why
bounces around five times?
Why don't I just put a mirror
right there and call it a day?
Great.
I had to look this one up, too.
So it bounces around five
times because otherwise it
would be upside down.
And who wants to look
through an image upside down?
Personally I don't, but
a lot of old view cameras
you do have to look at the
image upside down, because they
don't have any optics
to flip it over.
It's really easy when you have a
developed film to just do that.
But you have to actually
focus and compose
the camera upside down.
These were challenges I learned
when I was building cameras.
So the sensor and the shutter
are two different things.
So you will notice that
the light is not actually
going to the sensor or
the shutter right now.
We'll get into this in a minute.
Anyway, that whole
shebang flips up
and allows light to
get to the imager,
and then flips down,
in all the time it
takes you to press the button.
It seems complicated,
and honestly
it really is complicated.
There are many simpler
ways of doing this.
And the cameras you're
about to build are simpler.
And thank god, they don't have
all these moving parts to them.
It's great.
So we go into parts of
the camera a little bit.
We've got a lens.
We talked about shutters.
We'll get into
shutters in a second,
they're actually kind of fun.
Flashes, batteries,
sensors, LCDs.
This looks pretty familiar
to everyone, right?
Great.
Lenses.
This is fun, right?
Come on, we're having
fun, aren't we?
Excellent.
Good.
So lenses.
Here's a lens.
We can pass it around.
Don't drop it.
It's already been
dropped about five times.
Don't do it again.
It will be unhappy.
So we have wide angles
and long lenses, right?
Anybody have any idea
why the lenses have
different sizes in the front?
Please.
AUDIENCE: So you can
see more-- [INAUDIBLE]
ALEX LORMAN: No, no.
I see what you're getting.
And the answer is, sort of.
I don't mean to call you out.
But, it's sort of.
So this over here
is an 8 to 15 lens.
Who can tell me what
a focal length is?
Nobody.
Great.
Fantastic.
That's fine.
Don't worry.
So focal length is
how wide the lens is.
8 millimeters is really,
really, really, shockingly wide.
Like, it's like this.
In fact, that's a fisheye lens.
It's a really nice little
lens, but it's hugely wide.
And over there we have a
300 millimeter lens, which
is about this long,
costs more than all
of your first cars will, and
shoots-- focuses somewhere over
there to begin with, and you
can't really focus any closer.
But they're really
beautiful lenses
for doing certain things.
So we've covered what focal
length is between 8 and 200.
But the aperture is a big thing.
We talked about the aperture
and the iris in the lens.
You will not be able
to see through the lens
even if you look through it.
I promise you you'll
never get it to focus.
But it's a fun try.
So the big expensive lenses
let a ton of light in,
and that's why they're
big and expensive.
Seriously.
No, that is exactly why.
In terms of optics as well,
you'll notice none of these
are 8 to 200 because you
can't actually produce
good optics that do that.
It is not within the
realm of physics.
People try, and they
make really bad lenses
that do like 8 to 200.
And they're about this big,
and they're not very good.
That's OK.
Your lenses on
the Raspberry Pi's
are moderns of marvel
engineering-- of-- you
know what I meant.
All right.
So here's a fun bit.
Here's a video.
So shutters-- we talked about
shutters briefly, right?
They expose the imager
to light, and then stop,
and they do it in a
very precise timing.
So same thing as film.
So we're watching this at
10,000 frames a second.
And I think someone
is coming to talk
about high speed
cameras, which are
their own really awesome thing.
So we'll watch this again with
more narration, if that's OK.
If you all can tolerate
30 seconds again.
So we talked about the
mirror flipping up.
There goes the mirror.
This is in one exposure.
Now we see these are all
different exposure times,
so they let different
amounts of light in.
And you'll see that.
Watch the size of the
shutter as it rolls by.
There we go.
See one's much bigger,
one's much smaller.
Lets much more light in
versus much less light in.
And now the mirror
is coming back down.
So you see how phenomenally
fast this processes is.
And modern DLSRs can do this
on the order of 10 to 14 times
a second.
Which is really cool, and
sounds like a machine gun.
That's OK.
So the imagers.
These are the imagers.
Yeah, they're we go.
See?
That's roughly 8 to
10 frames a second.
They go quickly.
So in film, 10 frames
a second would last you
about three seconds.
And they actually invented
big, high capacity basically
magazines for stuff like
sports photographers,
that had 250 shots in them.
And you'd have a roll of
film that was about this big.
And they were horrible.
And some cameras got
away without the mirror
snapping up and down by having
something called a split
mirror, and let some light
through and some light up
at the same time.
So you basically got a
bad image in both places,
but you didn't have to flip
the mirror up every time,
so you could just shoot
the film through like there
was no tomorrow.
Sports photography is hard.
If you want to start
in photography,
sports is probably not
the place because you
need thousands and thousands
of dollars of equipment.
Don't worry about it.
This is a CCD.
I am not the right person to
tell you exactly how they work.
I'm sure one of the other people
that does this for a living
can, and can tell you how to
make them in your basement.
Which would be really cool.
But essentially they convert
light photons to electricity.
And then the computers
in the cameras
convert that to a picture, and
then write it to an SD card,
and we go from there.
So the cameras you're going
to building, like I said,
are marvels of
modern engineering.
All of that-- lens,
shutter, focus-- all of that
is built into something
that is absolutely tiny
and costs like $25.
It's amazing.
And actually, all of
the image processing
is on-board the camera as well.
And it sends it over
a communication bus
called SPI, which is a
standardized communication bus.
So it's actually incredible what
these little cameras can do.
And no, they're never
going to shoot as nicely
as the giant piece of
glass that's flying around.
But they're also on a chip.
How many of you use your
iPhones over a different camera?
Like a smartphone instead
of an actual camera?
Most of you?
Don't be shy.
It's OK to admit it.
There you go.
See?
So the marvels of
cell phone technology
have brought us to this.
And that's why you can
buy it for $25 or $30,
which is still
pretty incredible.
And the volume of production
for that is unbelievable.
There is a fun trick with
that lens, if you want.
If you can hold a
smartphone behind it,
you might be able
to get the image
to focus on the
smartphone camera
and shoot some kind of weirdly
distorted, and probably upside
down, picture.
It will probably be upside down
because the light is probably
crossing as it goes
through to focus.
Maybe.
You can do it with a set of
binoculars, too, actually.
AUDIENCE: [INAUDIBLE]
ALEX LORMAN: Nope.
Everyone's welcome to try it.
In fact I'll pass around another
lens and we can do that, too.
Again, they're all heavy because
they are really fast lenses.
Here.
That's another fun activity.
Go for it.
Just don't drop
that one, please.
I really like that one.
If I have to pick
one lens, that's
the one I go around with.
All right.
OK.
And please, you can
play with smartphones
and try to get a picture
if you desperately desire.
Like I said, the
Raspberry Pi cameras
are really stunningly amazing,
and you can do really fun stuff
with lots and lots of them
because they're so cheap.
And I think someone's
going to show you
how to do photogrammetric
scanning with them,
which is really cool.
But that concludes cameras.
Who has questions
about any part of that?
Because we really breezed over
like several hundred years
of development and
science in 20 minutes.
Who can explain how a
shutter works, roughly?
I clearly didn't
do a very good job.
Oh, no-- please-- save me.
No?
All right.
What does a shutter do?
AUDIENCE: [INAUDIBLE]
ALEX LORMAN: Please.
AUDIENCE: It lets light in.
ALEX LORMAN: Yeah.
Exactly.
Perfect.
Detector.
It's 10 points for
the scientific words.
Very good.
All right.
Excellent.
And apertures, again?
AUDIENCE: [INAUDIBLE]
ALEX LORMAN: Yep.
Perfect.
All right.
Fabulous.
I think I'm going
to hand it back
to whoever else is
running the show here,
because it's clearly not me.
And hopefully you
have enjoyed it.
And hopefully I get
all of the lenses
that I passed out
back at the end,
otherwise I'm going to
sit and cry in the corner.
I promise you,
there will be tears.
KRISTEN: Let's give him
a big round of applause.
[APPLAUSE]
ALEX LORMAN: Thanks, guys.
If anyone does have
questions, please fire away.
No?
Yes, please.
AUDIENCE: Why is that camera
called a Raspberry Pi?
ALEX LORMAN: That is a
question for the Raspberry Pi
foundation, who's
based in the UK.
And I honestly don't know.
No, but seriously, the
Raspberry Pi Foundation
is a nonprofit that
makes Raspberry Pi,
and they started making
the Raspberry Pi camera.
And that's what they do.
I don't have a better answer
than that, unfortunately.
Anybody else?
No?
If you really wanted
to get into like boards
produced by nonprofits,
literally the BBC--
like the news
organization-- just came out
with a tiny little
ARM based Linux board,
which they're giving away to
all school children in the UK.
Which is pretty cool, actually,
when you think about it.
Better yet, they've
included tools
to actually do things with it.
All right.
Thank you all.
Appreciate it.
[APPLAUSE]
