Many of us are familiar with the effect of converging verticals when photographing tall buildings, columns, and other perpendicular structures from the ground. As we step back and point the lens up to include the full height of the subject, it appears to lean towards the centre of the viewfinder instead of maintaining the straight, upright line that is the reality of its construction. This optical effect is a type of distortion that becomes more pronounced the wider the angle of view of the lens in use. It’s as if every building ends up looking like the Leaning Tower of Pisa.
In truth, most lenses have a degree of distortion, but the so-called ‘barrel’ distortion of wide-angle focal lengths is the most visibly apparent, particularly at the edge of the viewfinder frame. To avoid converging verticals, photographers have to shoot square-on to the subject and from a distance that allows them to include its full height, using a relatively distortion-free lens such as a short telephoto. However, this is rarely practical or even possible, particularly with prominent landmarks and skyscrapers, so a special type of lens is required – a Perspective Control (PC) lens.
Also known as Tilt and Shift lenses, these allow the photographer to tilt the lens when it is still fixed to the camera body and ‘straighten’ any converging verticals within the frame. Simply, the photographer begins with the lens in its normal position (mounted on a tripod) and frames the scene, making sure that the camera is level and the sensor vertical. At this point the shot won’t include the top of the subject, and there will be too much foreground, but by shifting the lens upwards, the framing is altered to include the top of the subject while keeping everything straight within the frame.
Large format origins
It is not just the photographers of architecture and cityscapes who find an advantage in the tilt and shift movements of these specialist lenses. For many decades (and well into the digital age) some landscape photographers used large format bellows cameras for the freedom of movement they provided to adjust depth of field and alter perspective without changing lenses or their shooting position. Add that flexibility to the larger format of these cameras and the resulting image quality, and it’s easy to see why some landscape professionals continue to use this kit today.
In design, build and function, today’s 5x4in and 10x8in cameras, made by Ebony, Linhof and Wista, closely resemble the cameras used by the pioneering photographers of Victorian times. They use sheet film and deliver an image far larger than any digital format sensor. The quality remains of the highest order and the large format camera’s capacity to make precise adjustments to perspective in order to correct distortions, gives them a huge advantage over other cameras. However, large format also means large in size and weight and this means the cameras are slow to use and transport. Also, only one exposure can be made per sheet of film.
Tilt and shift differences
In effect, the tilt and shift lenses made by Canon and Nikon for their respective digital SLR cameras are replicating the perspective controls and lens movements of these older-styled large format cameras. Canon has four such lenses in its range (17mm, 24mm, 45mm and 90mm) and Nikon three (24mm, 45mm and 85mm). Their specialist design and engineering means these lenses don’t come cheap. Nor do they use autofocus.
So what is the difference between tilt and shift lens movements and what are their other uses? In short, shift movements keep the lens parallel to the sensor, but move it up, down or from side to side, allowing the photographer to control the perspective of the image. Tilting the lens shifts the plane of focus so that it no longer lies perpendicular to the lens axis, resulting in a depth of field that increases in width further into the distance of the composed scene. The tilt effect allows the photographer to customise the position of the lens in relation to the subject. In other words, depth of field and image perspective can be manipulated quite markedly with tilt and shift lenses, in a way not at all possible with standard camera lenses.
In recent years a special effect made possible with tilt and shift lenses has increased their popularity among digital SLR users. The diorama effect, also known as ‘miniature faking’ or the ‘toy town’ effect is a technique that makes a photograph of a life-size location or object look like a picture of a miniature model. In these, only the central part of the image is clearly seen while other parts of the image are blurred to simulate the shallow depth of field normally associated with macro photography.
Not surprisingly, the ‘toy town’ effect is more pronounced when shooting down on the scene from an elevated position – much like the perspective of looking down on a miniature model – and tilting the lens up. Shooting from a high viewpoint also means that you can angle the camera more than when shooting at the same level as the subject. By tilting the lens upwards the plane of focus moves in the opposite direction to the way that the subject is positioned, thereby producing an extremely shallow area of sharp focus.
This effect is even more pronounced when setting wide apertures. Remember, PC lenses have to be focused manually, so when you’re ready to press the shutter, you will need to refocus on the area of the scene that you want to be pin-sharp, because tilting the lens completely alters the lens focus settings. This shallow depth of field ‘toy town’ effect has become the most popular use for tilt and shift lenses among digital SLR users – yet it is the complete opposite result to that sought by landscape photographers who use tilt and shift movements to maximise depth of field, particularly in the foreground.
As well as correcting converging verticals in architectural shots, creating the ‘miniature’ effect, or maximising depth of field in landscapes, there are a couple of other applications that can be used by these specialist optics. One of the simplest, and of particular appeal to landscape photographers, is the creation of a panoramic image.
To achieve this result, the shift movement of the PC lens comes into play: after setting up the camera on a tripod, all the photographer needs to do is take three exposures, one with the lens shifted left, one centred and one shifted to the right. Now, this optically-applied effect can be completed digitally by stitching the three images together in Photoshop or with other software such as Photomerge. The final stitched result is almost impossible to distinguish as three separate frames because of the camera’s single fixed position for each exposure. That said, these panoramas do not have the extreme angle of view obtainable from specialist panoramic cameras that use rotational lenses.
As any outdoor photographer knows, field obstructions such as posts and fences can sometimes hinder a desired composition and make it impossible to get the camera into a position that gives a clear view. In some instances, it may be possible to use the shift movement to alter the viewpoint sufficiently for the offending obstruction to move just beyond the edge of the viewfinder.
Focusing and general use
Although PC lenses do not work with autofocus, the focus points and focus lock confirmation in a digital SLR viewfinder can still come into use when working with one of these lenses. When focusing manually, simply select a focus point on your subject and use the focus lock LEDs in the camera viewfinder to confirm when your focusing or the lens tilt has brought this point of the subject into focus. When working with very shallow depth of field, this confirmation indicator can be most reassuring – a final check before pressing the shutter.
Tilt and shift lenses may seem like a more rarefied and expensive optic to have in your camera bag, but recent years have shown a diversification of their use from the original purpose of correcting converging verticals. Although built around optical principles that predate digital technologies by centuries, it is the onset of digital imaging that has extended their appeal. Digitally stitched panoramas and the ‘toy town’ effect have now become an important part of their allure. Like the sophisticated capabilities of today’s digital SLR cameras, these lenses need time to learn and master, but the effects they deliver can extend the photographer’s repertoire like no other optical accessory.
The Tilt-Shift Lens Advantage for Outdoor & Nature Photography by Darwin Wiggett & Samantha Chrysanthou; Oopoomoo; $20 (ebook)
Architectural Photography by Adrian Schulz; Rocky Nook; £29.99 (softback)
Using the View Camera by Steve Simmons; Echo Point Books & Media; £29.95 (hardback)
Lens option: Tilt and shift lens
Both Nikon and Canon make specialist tilt and shift lenses. These are fixed focal length, non-autofocus optics from wide-angle to short telephoto. Their specialist design, engineering and low production runs, mean they aren’t cheap (£850 to £1,480), but they have developed a following from those intent on exploiting the techniques only these lenses offer.
Accessory option: Tripod
Tilt and shift effects require a tripod, preferably one that is solid and rock steady. Gitzo and Manfrotto are the most reliable brands and the Manfrotto MT055CX PRO3 (£350) is ideal value for money. Fully extended shooting height is 1.83 metres and maximum load bearing weight for the head is 8kg – more than enough for most camera/lens combinations.
Camera option: View camera
These cameras may seem like museum pieces, but they still have distinct advantages over digital SLRs for manipulating depth of field and perspective control. The Ebony 45SU (£3,500) is a 4x5” view camera hand-made from ebony and solid titanium, with asymmetrical rear tilts and swings which allow for precise focus during adjustments. Front and rear adjustments and bellows extensions up to 20° are possible – considerably more than the 8.5° of Nikon’s PC lenses.
This was published in the March 2016 edition of Geographical magazine.