MANAGING DEPTH: WIDE-ANGLES, STITCHING & PERSPECTIVE BLENDING
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MANAGING DEPTH IN LANDSCAPE PHOTOGRAPHY IS FUNDAMENTAL. THIS YEAR’S FLAVOR IS PERSPECTIVE BLENDING. BUT, IS IT AS GOOD AS OTHER SOLUTIONS?
As humans, we perceive our reality as three-dimensional, while a photograph abstracts reality by compressing it on a two-dimensional medium. Luckily for us, as photographers we have many various tools that we can use to convey the idea of depth and of living in a three-dimensional space, when looking at landscape photography.
The first thing to keep in mind is that our perception of space as three-dimensional, when we look at a scene, is greatly helped by our perception of closer objects as being bigger than farther ones. Choosing wide-angle lenses, and composing wisely with them, is probably the most used, and one of the most efficient, tool at our disposal to create a sense of depth in our photographs. One of the proprieties of wide-angle lenses is, in fact, that of making closer objects look respectively bigger than they are, and farther ones smaller than they are, relatively to one other. Let’s call this the “wide-angle effect” on the relative size of objects in our frames.
Let’s see how the wide-angle effect works and how we can put it to a good use to convey a sense of depth. Consider a very popular example, one almost abused in today’s landscape photography.
Placing objects that we know from experience to be small, such as flowers, in the foreground, will make them look huge in the frame. Placing a mountain, that we know from experience to be huge, in the background, will make it look tiny in the frame. Playing with the relationship between the flowers & the mountain will allow us to create a sense of depth in our photograph.
However, while effective, this method presents some problems. First, managing the huge field of view of an ultra-wide-angle lens is compositionally not easy. Second, while successfully conveying depth, this method might make the background mountains, to stick to the example above, too small, sometimes so small as to become visually unimportant.
The first solution to this problem would be to step up in negative size, thus using longer lenses to cover the same angle of view. For instance, using medium format you can cover a 105 degrees angle of view with a 21mm lens, while to do so using Micro – 4/3 you’ll need to use an 8,5mm lens, with all the differences in look that this entails.
A second, classic alternative solution to portray a large angle of view while eliminating the wide-angle effect has been that of using what we’ll call here the “longer-lens-stitching technique”. Using a longer lens will obviously eliminate the wide-angle effect, while stitching an appropriate number of rows and columns for the situation will give you back the coverage you needed to begin with, therefore adding a sense of depth that a single, long-lens shot would not have.
Of course, stitching also has its limitation. Technically speaking, for instance, if you want to do a 2-minutes long exposure, and need to take 3 rows of 4 shots each, by the time you’ll get to your last shot the weather, the light, the position of the clouds, and so on will have changed dramatically, sometimes enough so as to make stitching difficult, if not impossible.
To overcome this limitation, you could use different exposures for non-moving areas of your images, such as landmasses, and for moving ones such as a cloudy sky or a moving sea. This is a bit tricky to do, in that you need to make sure that your exposures and light are balanced; on the other hand, it will allow you the possibility to widen your dynamic range in the process as well.
A second solution to this limitation would be to shorten your overall exposure, thus reducing the risks of making your final shots unmergeable. However, you might not always want to do that, for aesthetic reasons, if you need to use long exposures to convey your vision.
Finally, a third solution to this limitation would be – as counterintuitive as it might seems – to lengthen your exposure past the point where merging your images is difficult. What I mean is, if you use a long enough exposure to turn the sky or the sea water into a uniform expanse of color, then you can merge such parts of your final image to your heart’s content. Again, however, for aesthetic reasons you might not always want to do that.
More, aesthetically speaking the longer-lens-stitching technique can create the opposite problem to that it intended to solve. Instead of having images where the wide-angle effect is evident, and the foreground is too small, we have images that cover an ultra-wide angle of view, while looking like a tele-lens image. For those of us familiar with how lenses with different focal length draw, this is something that goes against our visual experience with lenses and the way they work in terms of coverage versus look. As everything else, however, this too is something that can be used for effect; but, also as everything else, longer-lens stitching too must be done when appropriate and must be done intelligently and tastefully.
Recently, a new solution to this problem appeared. Perspective blending, or focal length blending, is a technique that basically consist in taking one wider-angle shot for the foreground, one longer-lens shot for the background, and blend them in post-processing. Compared to long-lens-stitching, with perspective blending you’ll only need to take only one shot for the foreground and one for the background; this in turn will reduce the risk that changes in conditions between shots could make blending difficult, even when doing long exposures. So, while you’ll still need to merge two images, this technique will pretty much completely eliminate the merging problems created by the long-lens-stitching technique above.
However, perspective blending also has its problems and its limitations. The first limitation is a technical one. For this technique to be successful, of course your blending must be seamlessly perfect. If the blending area is evident, obviously the resulting image won’t work. If you don’t have a clear separation between the foreground and background, a visual “line” of sort in the landscape that you can use to “connect” the two shots, then a successful blending will become complicated, if not flat out impossible. This, in turn, will place some limitations to the number of scenes that you can actually photograph using this technique.
The second, and much more serious problem, is an aesthetics one. As I mentioned before, different focal lengths have different optical and aesthetic qualities and proprieties. The “look” of a wide-angle lens, thanks to the way it handles relationships between close and far objects, its very recognizable. So is the look of a longer lens, with its compression of distant focal planes. These aesthetic signatures are immediately evident when we look at an image, if we know how to look and where to look (see my THE ABILITY TO READ IMAGES article for details).
This, in turn, makes many of the images created through the use of perspective blending out there simply impossible to look at, for me. The problem is that half the image clearly shows a lens signature, the other half clearly shows a completely different one. Most commonly, the lower half, the foreground, features the perspective distortion introduced by the use of a wide-angle lens; while the top half, the background, features the compression created by a longer lens. Looking at one of these images as a whole, unfortunately, feels like looking at one of these distorting mirrors in an amusement park, i.e. those who distort your legs making them smaller while leaving your torso normal and making your head bigger.
The solution to this problem is, as always happens with any technique, to apply perspective blending intelligently and tastefully. Before trying perspective blending, you need to have a clear understanding of the optical properties of the focal lengths you use. Blending together two images created with focal lengths spaced far apart, i.e. a 16mm and a 75mm lens, will very likely result in a fairly unbelievable image, one where the aesthetic differences in look between the focal lengths you use fast become irreconcilable. On the other hand, blending together two images created with a 35mm and a 50mm lens, or a 24mm and a 35mm lens, will very likely result in a more balanced, more believable image.
In conclusion, all the techniques above are equally viable, each has their strengths and weaknesses, and each is useful to solve different compositional problems. Each can be used for effect, and each can be used to convey a powerful and convincing interpretation of a scene as well. If used tastefully and intelligently, each can prove an extremely useful tool to have in your bag of visual tricks.
As always, the most important thing we need to keep in mind when deciding which technique to choose to give our viewers a sense of depth and a feeling of space, is that technique must always be instrumental to realize your vision and achieve your artistic and aesthetic goals. Nowadays, unfortunately, too often we see photographic techniques used for their own sake, even if they don’t suit the subject matter at all.
Personally, I love to use wide-angle lenses exactly because of the different look they give to my images, and I use them very often to create my photographs. However, for such situations where I want to achieve a different look and a different effect, long-lens stitching and perspective blending are definitely great tools to have in my bag.
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