have you ever taken a picture of something that's got uprights in it
and then when you look at the shot you discover that the uprights are not upright?
They're bending around, they're either converging or diverging in the picture.
let me show you what I mean we've got a square sign just here or rather an
oblong sign.
if I take a picture of it from normal perspective sort of standing up here
like this. As you can see
the shot, the sign is wider at the top than it is at the bottom.
The verticals are going away like that, they're
diverging in the picture as it's getting wider as you look up the shot.
if we get down low the opposites gonna happen.
If I photograph it from down here
looking up at it and now
its wider at the bottom than it is at the top. So why does it happen?
if you don't have the sensor in your camera
parallel to the thing you're photographing
then one edge of it is gonna be closer than the other so when we're looking down on
something like this
the top of the sensor is closer to the top of the board which makes it wider.
The distance between the bottom of the sensor and the bottom of the board is
that it's further away and that's what makes those verticals
narrow to the bottom the same is true the other way up when I'm looking up at
something
like you would with a building or something like that the verticals are
narrowing as we look away so the way to straighten these verticals up
is to make sure that your sensor is absolutely parallel
to the thing you're taking a picture of. So if I line myself up
with the middle of this board about here,
go forward a bit and fill the frame, now if you take a bit of care you can really get it spot on
but quickly just to show you.
There you go, that's pretty much straight isn't it.
The question that's going on through your mind is well what am I going to do
when I've got a skyscraper or building or something tall to photograph because
It can't levitate,
strangely neither can I so what we need to do is to go and find a nice tall structure
and the way to do it is catch a ferry. Now what could be more vertically
challenging for a photographer than a
the lighthouse.
Converging verticals can make for some very very dramatic imagery.
I mean we just noticed look at the Lighthouse here with the Sun coming
round the edge of it.
if I just take a very very wide angle shot with the window in the bottom corner
and the Sun just kissing around the edge a bit.
That's quite a cool picture really isn't it?
but really we're here to control convergence as much as we possibly can.
so come with me I got side tracked. In that shot
I just took at the base of the lighthouse there I was looking straight up and making
use of converging verticals to make a dramatic image
and I said we're not supposed to be playing with them, we're supposed to be looking at ways
to correct them.
Now you could go out and spend a pile of money on a gift tilt lens which is a brilliant piece
of kit
which will correct all your vertical problems forever
but it's gonna cost you many hundreds of pounds and i'm looking for a more
low-cost
low-tech way of doing things let's just recap
quickly. so if the camera is tilted compared to your verticals you're gonna get
convergence.
so if I'm using a short wide-angle lens like this ten millimeter
I'm down here looking through the grasses because I think it will make a nice shot
and it will. What I get is super massive convergence going on
as you can see the whole thing is bending in towards the middle isn't it
now I know you can see the right hand side of the light house is
more than the left curling in more than the left
but if the lighthouse was smack in the middle of the shot it would be doing the
same
equally on both sides I included the square building on the left cause I like
the blockyness of it but you can see
it's curling that in towards the middle of the picture too, the whole thing is
tapering off towards a point but watch just by standing up
this is all I'm doing, look I'm not doing anything else and taking the same shot
that has minimized
convergence dramatically. What's the next step?
let's move back come on, just by walking over here, I'm gonna zoom my lens you wanna
make the lens longer so move myself back. You might have heard me go on about this before. I love this stuff.
Looking through the viewfinder I need to keep going to get my composition right
so keep coming back that's about there.
if I take the shot again but I've doubled the focal length I now am at 20 millimetres and
I'm standing up.
let's take that shot again here it comes
and that's even better isn't it, let's keep going and see what happens. I'm gonna have to
change lenses cause I've run out of focal length
on this one, my little wide angle zoom.
let's put on a longer lens, haven't got enough hands.
Let's dump this on here. We're gonna do the same thing,
I'm just making the focal length: a little bit longer again. I want to get as far
away as I can
and that's probably gonna be up against here. Now if I just
recompose my shot, focus on the lighthouse
and that's almost perfect isn't it.
why is it happening well it's because
when we're right underneath the lighthouse the camera is like this and
my sensor is
at this angle but the lighthouse is at that angle.
As we move back if I didn't tilt the camera down I'll be looking at the sky
wouldn't I so as I'm coming back
I'm tilting the camera down. As you can see as I tilt the camera down
it's bringing this angle and that angle closer together
so the convergence decreases. There's one other thing I could do here
quite lucky
in that I've got some stone steps,
so let's raise myself up a bit and see what happens, I wanna get as high as I can
so I'm gonna stand right up here.
I now must be a good what, 8 or 10 feet higher than I was over there.
let's recompose the shot and take a look.
Oh I can see straight away that is better, that is much better.
Yes as you flick between those two,
yeah there's quite a difference. Even just coming up here
it's quite astonishing isn't it . Now if we had permittion
which we don't to enter and film in a national trust property
we could climb up on top of this wall here, we could pay the entrance fee and go
into the castle
from there you can be much much higher up and it's far more likely you'll be
able to get a nice straight picture of the lighthouse.
now there's of course a software you could use, programs like adobe Photoshop
they have straightening tools within them which will help
but the better quality the more straight you have your verticals
in the image file the better job you'll be able to make in post-production.
now there's one final thing I have to confess this lighthouse
is a bit narrower at the top than it is at the bottom
lighthouses do that but I have to say
it's nothing like is narrow at the top in reality as it
is in that picture.