Creating compelling images involves a lot more than mere exposure considerations. Subject choice, positioning, framing and context (both physical and social) all play an important role, as do lighting, colour, form and texture.
But there’s another crucial ingredient that can have a profound effect on the impact and message of your photos – one that’s often overlooked: visual perspective.
Visual perspective describes the apparent size, distance and spatial separation of objects in three-dimensional space as determined by their position and distance from the eye. The basic principle is that to the human eye, objects in recession appear to get smaller as their distance increases, causing the space between parallel lines to gradually diminish. When infinitely extended, parallel lines appear to meet at a single point of intersection on the horizon.
The way in which railway tracks appear to converge towards a distant vanishing point is a classic example of the phenomenon, but you can see visual perspective at work almost everywhere. Next time you’re outdoors notice how the vertical walls of tall buildings appear to slant together towards the top, and how houses or trees in a row appear to shrink as they recede into the distance - an effect that can be used creatively for commercial photography and architectural photography.
You can get another interesting perspective if you kneel on the floor and get a friend to lie down directly in front of you with their feet facing you. Look down the line of their body and observe how disproportionately large their feet look in comparison with the size of their head – classic visual perspective at work once again.
How to take control
By altering lens focal length in conjunction with your distance from and viewpoint of the subject, you can exert enormous control over the way three-dimensional visual perspective is represented on the two-dimensional photographic plane. Depending on the combination of focal length, distance and viewpoint employed, you can reproduce perspective in the classical sense for a natural view of depth, or distort it to create more exaggerated, artificial representations of depth.
First let’s consider the effect of varying subject distance on perspective. Imagine that you’re looking down a wall of uniform height from an oblique angle. The end closest to you will seem much higher than the end furthest away. The difference between these two apparent heights is a direct ratio of their distance from you. For example, if the near end is 2 metres away and the far end 16 metres away, the height ratio is 1:8 which gives a steep, elongated visual perspective. But if you step back until the near end is 10 metres away and the far end 24 metres away, the height ratio drops to just 2.4:1, creating a much shallower, compressed visual perspective.
How to Influence the Visual Perspective of your Subject
Using a wide-angle 18mm lens and placing the subject one metre away the perspective will be at it’s steepest, creating a strong impression of depth of field.
Using a 60mm lens and increasing the distance to subject to a couple of metres – the background at infinity will seem far larger than before and the scene will have less apparent depth.
Using a 135mm prime lens – again with the subject a couple of metres away the background detail at infinity increases in size dramatically and subject and immediate background detail start to crowd in on one another.
The long and short of it
Varying focal length cans strongly influence photographic perspective. Shorter focal length lenses tend to stretch linear perspective. This makes foreground objects (especially those close to the lens) seem bigger than they would in reality, while background objects appear much smaller. The apparent convergence of parallel lines is also exaggerated, giving a greater impression of depth of field and distance.
Telephoto lenses have a noticeable effect on perspective too, making objects at different distances appear much closer together than they really are and reducing the apparent convergence of parallel lines. By minimising the apparent scale change between foreground and background objects long focal lengths can also create an extremely distorted impression of scale - an effect often used in commercial photography. A standard 50mm focal length meanwhile will give the truest, most natural representation of perspective as the human eyes sees it.
By carefully combining a change in subject to camera distance and position and a change in focal length, you can radically alter the impression of size, spatial separation and distance conveyed by your compositions.
Steep Perspectives
To create a steep perspective, use the shortest focal length setting in combination with a close-up viewpoint. Use this combination to:
- Emphasise distance and/or the differences in spatial separation between receding objects – perfect for landscapes.
- Make foreground elements dominant by exaggerating their size in relation to secondary background elements.
- Exaggerate the apparent height of a building and create a dynamic, looming composition.
- Create distorted caricatures with oversized eyes, noses or other elongated body parts.
Shallow Perspectives
Conversely, to create a shallow, compressed perspective, use a long focal length in combination with a distant view. Use this combination to:
- Reduce the apparent distance between objects. - Minimise scale change between foreground and background elements in the image. - Make receding objects appear squashed up on top of each other (great for crowds, traffic jams or groups of buildings). - Also to merge foreground, middle ground and background into a flat plane. - Magnifying the main subject and isolate it from the background. - Create flattering portraits with better proportional facial features (80-150mm, 35mm format)
Digital Perspective Control
Most image editors feature one or more tools that enable you to both accurately and convincingly correct undesirable converging verticals in buildings and other tall structures. Photoshop’s first option – the Perspective tool – can be found in the Edit -> Transform submenu alongside a selection of associated adjustment options: Scale, Rotate, Skew and Distort.
To use the Perspective tool you drag the bottom corner handles of the frame inwards (to make life easier choose View -> Show -> Grid first). This restores a less slanting, more natural looking perspective to the top end of the structure, but it does require you to crop the sides of your shot. If the height of the structure appears slightly elongated the Scale tool can be used to restore it.
The Crop tool provides a great alternative for correcting converging verticals. Once activated, a Perspective checkbox appears inside the Options Bar. Check this then use the handles to position the bounding box so that it lines up with the walls of the building whose perspective you want to correct. When you apply the crop the converging lines become vertical.
The Warp tool in Photoshop (Edit -> Transform -> Warp) offers other perspective manipulation options, enabling you to fake fisheye distortions or simulate stretched perspectives in landscapes or buildings. Also the Vanishing Point tool enables you to clone, heal, paste, paint and transform objects in a way that automatically matches the visual perspective of the scene.
Perspective control lenses (also known as PC or shift lenses) are specialist tools commonly used for professional architectural photography and commercial photography. Their main purpose is to enable you to shoot buildings and other tall, geometric structures without converging verticals. They can also be used to create panoramics from two exposures or double up as ordinary wide angle lenses.
Shift lenses work by enabling you to move the lens elements upwards, downwards or sideways to shift the apparent viewpoint, without having to tilt the camera to fit the top of your subject in.
This article shows the quality and variety of techniques that customers benefit from as part of our commercial photography and architectural photography service. Call now to discuss your requirements and timescales on 079101 68536.
