“Perspective” is the technique or process of representing a scene on a two dimensional plane so that the objects represented have apparent depth and distance. This three part assignment will explore the primary techniques for conveying depth and distance and controlling perspective in an image.
The last two assignments, “Balance” and “Soft Light,” were natural lead-ins to this multi-part assignment on “perspective.” In the “balance” assignment, the goal was to balance the “weight” of compositional elements within the frame. While some of the images succeeded, others were not quite balanced. In the images where the photographer was attempting to balance a nearby object with a distant one, how effectively they controlled the perspective (the apparent size and distance relationships of near and far elements) played a key role in whether they were able to successfully balance the image. One of the techniques we will talk about during this assignment is how to use focal length selection to modify the size relationships of near and far elements in the scene.
“Soft light” dealt with the use of soft, diffused lighting sources to provide “dimensionality” to a subject and “depth” to an image. “Dimensionality” and “depth” are key components of “perspective.” The gradual transition of shadows from dark to light as they “wrap” around an object are one of our primary visual cues as to the shape and thickness or “depth” of nearby objects in a scene. As we talked about during the “soft light” assignment, the absence of shadows results in a 2-dimensional image, while the presence of “soft” shadows, results in the perception of 3-dimensions. We use these cues in conjunction with other visual cues to build an overall impression of depth and distance for the scene. These other visual cues are often segmented into two categories, “linear perspective” and “atmospheric perspective.”
Linear Perspective. Linear perspective deals with the way we use converging lines as cues for determining distance and size relationships between near and far elements. In the example below, the converging lines of the railroad track provide relative scale from which we can determine the distance and size of the train. We use both the rate and amount of convergence to assess distance, and from that determine the relative size of objects at that distance.
Be aware that the converging lines do not have to be “linear” in the strictest sense (i.e., a straight line). The converging lines of a winding road or river can be very effective at “leading” the viewer into the scene and providing a sense of relative scale based on the amount of convergence.
Even without clearly defined converging lines in a scene, our minds will perceive distance based on transitions in size between near and far objects, such as in the example below. The change in size of the lupines from the foreground to the background provides a definitive cue as to the distance between them.
This image illustrates how converging lines, vanishing points, and atmospheric haze result in a perception of distance.
. In addition to “linear perspective” we also use “atmospheric perspective” to perceive distance in a scene. Atmospheric perspective deals with how the appearance of an object changes when we view it from a distance. Moisture, dust and pollution in the air interfere with light transmission and result in objects in the distance having less contrast, less saturated colors, and “hazy” or blurry detail. We subconsciously use these visual cues to perceive these “hazy” objects as being far off in the distance.
Controlling Perspective. We can (and should) use all of these techniques to provide a sense of depth to our images. Variations in the sizes of nearby and distant object often provide the most compelling sense of depth, since judgments of distance in real life are based largely on the apparent differences in size between near and far objects. We can use this to our benefit if we understand that focal length selection has a dramatic effect on the relative sizes of foreground and background elements and our resulting perception of depth.
Because a shorter focal length lens results in the foreground elements appearing larger in relation to the background elements, we can use a shorter focal length lens to convey an “expanded” perspective. The effect of expanded and compressed perspective is illustrated in the two images below. Both images were taken at the exact same location on the bank of Oxbow Bend in Grand Teton National Park. The first image was photographed with a 28mm lens, which expands the perceived distance between foreground and background elements. The far bank of the river looks much further away than it really is.
The second image was photographed from the same position with a 200mm lens, which compresses the foreground and background elements in the scene. The trees look much closer than they really are, and the perceived distance between the trees and the mountains has been compressed.
We can also use focal length modify the relative scale of objects in the scene in order to emphasize selected elements. A shorter focal length lens will emphasize the foreground elements, while a longer focal length will emphasize the background elements.
Most tourists that photograph this scene below in Grand Teton National Park want to replicate the pictures they have seen of this now famous barn dwarfed by the “Grand” Teton Mountains in the background. Unfortunately they don’t succeed, because they photograph from the road, and use a wide angle lens to fit the barn in the image, as seen below.
In order to successfully emphasize the scale of the mountains in relation to the barn, the savvy photographer will hike much farther away from the barn across an adjacent field, and photograph the scene using a long telephoto lens.
Hopefully by now you can see how changing focal lengths could have been used to help balance compositional elements for images submitted in the “balance” weekly assignment. I’ll use this image as an example:
Although this is a very nice stock photography “location” shot, I feel it could have been a bit stronger if the sign and background rock formations were better balanced. This could have been achieved by stepping further back from the sign (if possible) and using a longer focal length lens to bring the distant rock formations in closer and deemphasize the sign. The resulting image would have looked something like this:
This technique could have been used for several more images in the “balance” assignment in order to better balance foreground and background elements.
The assignment for the week of 14 – 20 July is “Linear Perspective,” which will be the first of a three part exploration of techniques for conveying and controlling the perception of depth in a scene. For “Linear Perspective” you should use converging lines to draw the viewer into the scene and establish a sense of distance and depth, or use transitions in size between near and far objects to provide a “relative scale” from which we can derive a sense of distance and depth. Curved lines (especially an “S” curve), can be very effective a drawing the viewer into and through the scene, while providing the cues used to perceive depth. Don’t forget to use techniques we learned in the “balance” assignment to provide a pleasing composition and balance between primary and supporting elements in the scene.
We will explore “atmospheric perspective” and “controlling perspective through focal length selection” in follow-on assignments.
As always, have fun! Please upload your images to the “Linear Perspective” album in the “Weekly Assignments” category by midnight Mountain Standard Time (GMT -07:00) on Sunday, 20 July 2008.
Keith
