Tilt/Shift: Working With Perspective-Control Lenses, Part 2Gear Talk
This is Part 2 of a series on using Tilt-Shift or Perspective-Control lenses. In this part, we look at the “Tilt” functionality of these unique lenses. Part 1, which covered “shift” functionality, can be found here.
At some point in time, we’ve all seen photos where the subjects – usually views from high-up of cars, buildings, people, etc. – appear to be miniaturized versions of reality. This is perhaps the most the most often-seen result from using tilt-capable lenses like the Nikon 85mm PC-E.
In this part of our series, we’ll explain how this effect is achieved with tilt-shift lenses.
The image below was shot by Jim Goldstein, our Marketing VP. Taken in Geneva with a tilt-shift lens, the camera was pointing downwards at the railroad tracks, with the tilt element swung upwards.
The reason these tracks look like miniatures is because the plane of focus is so narrow, that both the foreground AND the background are out of focus. That’s not something the human eye is used to seeing, and we interpret images like this differently. Wikipedia adds to that explanation as follows:
Diorama effect or “diorama illusion” is a process in which a photograph of a life-size location or object is made to look like a photograph of a miniature scale model. Blurring parts of the photo simulates the shallow depth of field normally encountered in close-up photography, making the scene seem much smaller than it actually is…
Now, in order to achieve that effect, you have to swing the front part of your tilt-shift lens in so that it is either as perpendicular as possible to your subject, or is at an obtuse angle to your subject, as shown below.
Doing so minimizes the depth of field in your image, resulting in a very narrow slice of the subject actually being in focus. The results of this technique are shown in Jim’s image above. Swinging the lens away from your subject, in other words, miniaturizes it.
The technique takes some practice to get right. I’ve found that it’s easier if you try and shoot from a pretty high place, and try and eliminate as much of the sky from your shot as possible.
Of course, perspective-control lenses swing the other way too (no pun intended). Landscape photographers (and some product shooters) may already be familiar with this technique, and it’s extremely handy to maximize your depth of field.
To do this, swing the lens in such a manner that it’s at a more acute angle to your subject’s plane, as shown below.
Let’s look at a practical example of this.
What you’re looking at below is a device we rent called a LensAlign Pro. It’s used to test autofocus accuracy for cameras and lenses and is a handy tool to have.
In this shot, the LensAlign Pro is shot at f/2.8 with a Nikon D800 and an 85mm PC-E lens. The lens is not tilted, as shown below.
If you look back at the LensAlign, you’ll notice that there’s a sort of ruler on the right that I’ve laid back at a pretty steep angle to demonstrate the effect of tilting the lens on depth of field. Let’s take a look at a 100%crop from that shot.
As you can see, only the ’0′ and part of the ’8′ above and below the ’0′ are in sharp focus. That’s to be expected at f/2.8 – the wider open your aperture, the narrower your depth of field.
Now, let’s tilt the lens down, as shown below.
Now, let’s take a look at the LenAlign’s ruler. Remember, we’ve not changed the aperture, which is the way most lenses control depth of field.
As you can see, the change is pretty drastic. We’ve gained a lot of depth of field without changing aperture.
This technique of using the tilt mechanism is often ignored, which is why I spent some additional time on it. The first question people ask when I explain this function is, “Why don’t you just make your aperture smaller?”
Indeed, making your aperture smaller is a valid way to increase depth of field, but there are also many reasons why you would not want to do that.
For example, let’s say you’re shooting a field of wildflowers and want a pretty deep depth of field. You stop down to f/8 or f/11, which is where many lenses perform best. You could go all the way to f/22, but beyond f/16, other factors come into play that can hurt your image. Lens diffraction, for example, is one of them. The folks at Luminous Landscape have a nice piece that explains what this means, but basically, beyond a certain point, your image actually begins to lose detail as you make the aperture smaller.
Exposure is another reason why making your aperture smaller may not work. The smaller your aperture, the slower your shutter speed and/or the higher your ISO, both of which bring their own pitfalls. If you’re shooting handheld, slow shutter speeds would result in motion blur, whereas kicking your ISO up to compensate would increase noise.
While it is true that in many cases, there are ways to gain that depth of field through other means, knowing about these features of PC-E lenses is one more thing you can add to your arsenal. And that, folks, is never a bad thing.
As always, questions and feedback are welcome in the comments below.
UPDATE: As Aaron, one of our readers, points out below, tilting the front element doesn’t actually increase your depth-of-field; it changes the angle of your DoF. You effectively gain the benefits of an increased depth of field, but only for the plane that your subject is on. That’s a good distinction to make.