What if I told you there was a special type of lens that among many other cool uses, allows
you to take a picture of a mirror, straight on, without getting any of the camera in the
reflection at all.
Yes, there is such a thing, and I’m going to tell you about it, so prepare to have your
mind blown.
Before we jump in, it is essential that I do my shameless plugs of course.
If you haven’t seen my incredible Instagram account, it has the most amazing tech memes
you could possibly imagine, so be sure to check that out, it’s just @ThioJoe over
on Instagram if you want to collapse from laughing so hard.
And with all that out of the way though, let’s get started.
These days, considering everyone has a camera right in their pocket, when it comes to taking
a picture you’ve probably got it figured out.
You just make sure the thing you want to photograph
is in focus so it’s not blurry, and then
the things in front and behind it a certain distance will be out of focus.
But there is one type of lens that most of you have probably never heard of, that will
completely change what you think you know.
It’s called, a Tilt-Shift lens.
And even if you have heard of it, you might just know it as that weird effect that makes
things look miniature, but the capabilities of these lenses are so much stranger than
that.
So let’s get into what these lenses can do.
The two unique abilities of these lenses are called Tilting and Shifting, wow big surprise.
The first one we’ll go over is shifting, which is actually really easy to understand,
and allows that weird ability to take pictures of mirrors I mentioned at the beginning.
You see how every lens works is the light comes in one end and out the other end, projecting
what’s called an “image circle”, and then you put the image sensor or film in that
circle, and it captures a portion of it to form the image.
The bigger the sensor size, the bigger the image circle needed to cover it.
A normal camera lens you buy is specifically designed to have an image circle just big
enough to cover the sensor.
But a tilt shift lens is different.
It has an image circle much larger than a typical lens.
And on the lens itself, allows you to literally shift the lens side-to-side or up-and-down,
therefore changing where the sensor is located in the image circle, therefore shifting the
image.
You might think, well what’s the point of that, why not just move the camera itself
left or right, or put it higher up on the tripod.
But it’s not the same.
A shift of just a few millimeters may be equivalent
to moving the lens anywhere from a few feet
to a hundred feet or more, depending on the focal length.
This allows some abilities that would be impossible
with a regular lens.
For example, if you wanted to take a picture of a tall building, you’d probably have
to point the camera upwards, which makes the building look warped, with lines converging
towards the top.
With a tilt-shift lens though, you can just point the camera level with the ground, then
shift the lens up, so the lines all stay parallel and vertical.
To do that with a normal lens, you’d have to buy high up in the air at the center of
the building to get the same picture with the vertical lines.
And now here’s how to do the thing with the mirror.
If you want to take a picture of a mirror with a regular camera without being in the
reflection, you have to stand way off to the side and turn the camera at a strong angle,
which is very obvious that you’re not looking straight onto it.
With a tilt shift lens, you still need to place the camera just off to the side of the
mirror, but you can point it perpendicular to the mirror, then shift the lens, so the
perspective looks like it’s just pointed directly into it, but it’s not.
Shifting is also good for taking panoramas you stitch together.
You can simply shift the lens to the sides, taking multiple pictures, then stitch them
together, so you don’t have any weird distortion like you might get if you did the same by
turning the camera.
So that’s shifting, but what about tilting?
Well this is actually my favorite, and it’s where things get really weird.
As you probably know, when you focus a camera, there’s a plane of focus that you can move
forward and backward.
And that plane is always parallel to the sensor or film, called the sensor plane.
But when you tilt a lens, and keep the sensor plane the same, something very strange happens.
The focal plane actually rotates and tilts in the same direction as the lens.
This allows you extreme control over what’s in focus, so say you have a row of objects
you all want in focus, instead of having to reduce the aperture to increase the depth
of field, you can just rotate the depth of field so it’s still shallow, but still gets
everything in focus.
For example, a lot of landscape photographers actually use tilt shift lenses, then tilt
the focal plane forward, so they can basically get the entire landscape perfectly in focus,
instead of just focusing on infinity and sacrificing
some of the focus closer in the scene.
Another cool use is the “miniature” effect you’ve probably seen, and this is actually
the result of aiming the whole camera downwards, and then tilting the lens upward, therefore
tilting the focal plane backwards.
This results in only a tiny amount of the scene intersecting with the focal plane, therefore
creating a very shallow depth of field, despite being not being zoomed in.
So it tricks our brain into thinking we must be zooming into something very small.
Now I still want to clarify some things, because the way the focusing works is not as simple
as tilting the lens, and the focal plane tilting by the same amount.
The actual way the focal plane relates to the tilt is called the Scheimpflug principle,
but I’ll try to simplify it as best I can without getting into the math of it.
Basically as you tilt the lens, imagine some lines extending from the sensor plane, the
lens plane, and the focal plane.
When there is no tilt, all of these are parallel and vertical.
But, as you tilt the lens forward by any amount, what happens is the focal plane also tilts
by an angle such that all three planes intersect at a single point, no matter what.
This means the actual tilt of the focal plane is determined by both the tilt angle of the
lens, and how far the lens is from the camera.
An interesting consequence of this, is that when the lens is tilted, if you try to focus,
that also rotates the focal plane further.
So you can get a ton of tilt from the focal plane, with just a tiny bit of tilting the
lens, yes, even to the point of the focal plane literally being perpendicular to the
sensor plane.
Now if all this sounds amazing, you might be surprised to find out that none of this
is new.
The exact math of the Scheimpflug principle was derived right around the early 1900s,
but photographers knew about using tilting and shifting in lenses since the very beginning
of photography itself.
In fact, back in the days of cameras with bellows, they were basically ALL capable of
moving the lens around to do the same movements as a tilt shift lens.
So this is a rare instance where modern cameras actually lost a feature that used to be in
all cameras.
These old style cameras are still around though, and if you follow me on Instagram you may
have seen my large format camera I bought recently.
This is a field camera so it’s made to be slightly more portable than other big bellows
cameras, but it still can do almost all the same movements I described.
So you can shift the lens any direction, and also tilt the lens side to side or forward
and backwards.
What’s nice about these old style cameras is you can do all these movements no matter
what lens you use, as long as it covers the film obviously.
And you can also tilt or shift the lens any amount, even to an extreme degree, as long
as the resulting image circle can still cover the film.
So fun fact, one spec you need to consider when buying an old lens like this, is the
size of the image circle it produces, which is never something you need to consider with
modern lenses, because they’re standardized and don’t need to do any tilting and shifting.
Now there are some other things I should point out in regards to tilt-shift lenses.
When it comes to shifting, you might be wondering if instead of shifting using a tilt shift,
you could just use a wider angle lens.
And actually, yes, technically you could.
If you were to look at the full image circle from a tilt shift lens, it would produce the
same image as a wider angle lens.
But the difference is, with a wider angle lens you have to use the whole sensor on the
whole image, so to get the same image as a tilt shift lens, you’d have to crop it down
a lot, therefore losing a ton of quality.
A tilt shift lens basically lets you take a really wide angle lens, but only capture
whatever part of it you want, and at higher quality because you’re using the whole image
sensor on just that part.
Make sense?
But remember, that just applies to the shifting.
You can’t replicate the tilt feature using any other lens, you need one that can physically
tilt the lens.
Now by this point you might be wondering how to get your hands on one of these lenses.
And unfortunately, they’re some of the more expensive lenses out there.
Because not only does the manufacturing have to provide additional controls for tilting
and shifting for features, they also need extremely high quality optics to be able to
project such a large image circle.
An alternative to shifting could be to just get an extremely wide angle lens and cropping
it down, but remember that will reduce the resolution of the image substantially.
As for tilting the lens, you might see lots of photo editing effects like on Instagram
called “tilt shift”, which can do the effect where it blurs everything except a
certain part of the image.
But these obviously can’t do the more useful ability of a tilt shift lens, which is to
get more in focus.
Now one possible exception to all this would be tilt shift adapters, which would go between
the camera sensor and lens, then allow you to add tilting and shifting.
I know there are tilt shift adapters for really high end cameras like hasselblads, but I’m
not sure if they really exist for typical full frame or even APS-C. So you might be
able to do a lot of searching and find something like that, but I haven’t seen too much about
it.
And anyway that pretty much covers it, let me know what you think down in the comments.
The next video I’d recommend watching is one I made with 10 awesome computer accessories
under $50.
I’ll put that link right here if you want to watch that.
So thanks again for watching guys, be sure to subscribe and let me know what you think,
and I’ll see you in the next video.