Shallow depth of field by means of a wide aperture emphasizes a landscape in compelling ways, stepping outside the everything-sharp genre, while encouraging spontaneous creativity and freedom of movement without a bulky tripod.
In daytime lighting, our usual inclination with landscape photos is to eagerly stop down for increased depth of field, to equalize sharpness everywhere. But equalizing sharpness near-to-far places the same sharpness emphasis on everything in the composition, which does not by itself make a stronger image. Eliminating the powerful tools of sharpness and blur by always stopping down makes one’s imaging toolkit less flexible, promoting reduced creativity.
With a lens set to a wide aperture such as f/1.4, the combination of vignetting and minimal depth of field focuses the viewer’s attention sharply, even if the over- all image is less sharp. Thus, less sharpness overall might mean that more is communicated.Observe that a telephoto lens is often used for its benefits of isolating a subject; a wide aperture exerts similar visual power.
From a perceptual standpoint, sharpness is relative. The in-focus eyes seen in a portrait stand in sharp comparison to out-of-focus elements, none of which need to be sharp in a portrait context.
Landscape images with pin-sharp details everywhere are by default about the entire scene, yet many compositions feature a single item in its context (a boulder, a tree, a mountain peak, an animal). The surrounding elements are important, but in most cases are needed only for contextual support. With everything equalized in sharpness, the eye and mind lack guidance other than the spatial arrangement of elements in a 2D plane—why should compositions not also direct the viewer’s attention using sharpness differences, making use of 3D visual cues?
Out of focus elements in the scene can communicate more quickly, and perhaps more subtly, because the mind is free to perceive in an orderly way, focusing attention on one element, with environmental information settling into place, perhaps even unconsciously. Sharpness everywhere impedes intuitive perception of the whole, just as we cannot perceive everything at once in reality; we must focus on something in particular to be fully aware of it. While brilliant landscapes with blue sky, clouds, flowers and everything pin-sharp are “pretty,” I rarely find those scenes very interesting any more; I’ve felt a personal need to seek out new approaches that don’t remind me of the postcard look. Since every lens “draws” with its own style wide-open, creative options emerge that are not possible with a lens set to f/11. To date, my favorite lens for such work is the Leica 50mm f/0.95 Noctilux-M ASPH.
A wonderful benefit of shooting wide open is abandoning the tripod, allowing more creative exploration, a wider variety of shooting angles and a less stressed neck and back.
Minimizing depth of field
For maximum separation of subject from background, a lens with a wide (bright) aperture is needed, such as f/1.4. Ideally, the lens should be a strong optical performer wide open, to maximize the interplay between sharp and unsharp. But this is not a hard requirement, and in some cases technically inferior optical performance can produce a pleasing “look,” so long as the effect is not one of distracting aberrations, such as excessive veiling haze from spherical aberration, or bizarre misshapen points of light off-center. Yet such technical flaws themselves can add interest, so there is no bad lens.
Vignetting as a tool
Darkening at the corners is essential to directing the viewer’s attention, as is the shallow depth of field, so be sure to disable any vignetting correction in your camera or computer software.
Since vignetting can darken corners and edges by over three stops, daylight shooting can feature backlit subjects near the center of the frame that are thus in good balance with much brighter areas near the edges and corners, such as bright clouds. With some lenses, color vignetting (color shading), results in a blue/cyan color cast away from center, which can be used for perceptual effect, further emphasizing the sense of space from center to corners.
Examples were chosen for variety. Subtleties are lost at a small size; even a blurred image looks sharp when small enough. My preferred print size is in the 24×16 or 30×20 range.
Figure 1 shows a portrait of an ancient bristlecone pine high in the White Mountains of California (Leica M9 +50/0.95 Noctilux-M ASPH). An f/1.2 or f/1.4 lens can achieve similar effects, though reduced versus f/0.95.
The technical flaws of vignetting and a razor thin zone of sharpness imbue this image with a precision of at- tention; sharpening the background by stopping down would make the background compete with the tree. Yet ample contextual information remains.
Figure 2 shows a classic landscape image made with the Nikon 24/1.4G on the Nikon D3x at f/1.4. The high- key effect with the pale blue sky is true to the conditions; it is not a lens effect, but the overall lower contrast is a lens effect, and not one I’d change in favor of the saturated blue-sky postcard look. The vignetting is probably not noticed immediately, but it brings the viewer’s at- tention to the bridge. The shallow depth of field exerts a gentle pull on the viewer, which is accentuated by the composition itself.
Figure 3 shows one of my favorite pursuits for landscape photography: finding faces or animal shapes in nature. Shallow depth of field must be used carefully when making images at close range, lest it distract by blurring too much. Vignetting aids this image, includ- ing toning down the bright clouds at upper left.
Figure 4 was shot at f/4, which provides an equilibrium of sharp/unsharp, while ensuring that the small tree is sharp enough over most of its area for the image to succeed without overt subject blur.
Neutral Density Filters
Shooting wide-open can require a shutter speed faster than the camera maximum. A neutral density filter brings the shutter speed down to a more reasonable one.
On the Leica M9, the top shutter speed is 1/4000. In sunlight, this is not fast enough to make a proper exposure at f/1.4, let alone f/0.95, even at ISO 80. At the real ISO of 160, a shutter speed of 1/32,000 second might be needed for snow or beach, but no camera has such a speed. And so a neutral density (ND) filter is mandatory to allow for daytime shooting. A 3-stop ND filter is the best all-around choice, but the ideal scenario is to have 3/2/6/10 stop ND filters.
Shooting tips for wide aperture landscapes
Ignore the rule of thirds — center the subject. The com- positional balance of the image is greatly affected by vignetting and the sharpness gradient throughout the frame. A centered subject works well in most cases because the vignetting and overall blur emphasize the center. Symmetric or semi-symmetric subjects generally work very well. Many exceptions exist, with the lighting conditions affecting the compositional balance—break the rules!
With a wide aperture, very little is in focus, so choose a center of attention and focus precisely, just as you would do by focusing on the eyes of a person or animal.
Focus as accurately as feasible, focus bracket
Misfocus breaks the effect by placing emphasis on the wrong portion of the subject and/or blurring the desired subject. Shoot multiple frames to obtain a frame with a focus just right for the subject.
Vignetting is your gradient filter
Don’t stop down, or you’ll lose the vignetting effects, which are a valuable tool for focusing attention on your subject.
Shoot multiple apertures f/1.4, f/2, f/4, /8 or similar; you might prefer the effects at one aperture over another. In some cases, layering multiple images shot at two different apertures can be intriguing.
The net effect with a wide aperture image is the sum of many optical properties: sharpness and contrast, bokeh and color bokeh, lens aberrations, field curvature, the veiling haze of spherical aberration. It’s the overall visual impact that matters, not absolute sharpness everywhere. Understand the behavior of your lens, because when shot wide open, effects arise that are suppres- sed when a lens is stopped down.
Even the best fast-aperture lenses have substantial aber- rations wide open, which makes focus somewhat ambiguous, particularly off-center. Therefore, the expectations for crisp and contrasty results must be reduced. This is true even for the exotic Leica 50mm f/0.95 Noctilux-M ASPH, which has a highly unusual construction with numerous special-glass elements.
The primary challenge when working with wide apertures is focus accuracy. While autofocus can sometimes be relied upon, this is often not the case because of the lower contrast of wide-aperture lenses, which reduces autofocus accuracy. Accurate manual focus is also a serious challenge at wide apertures. Ensure accurate focus using a Live View feature if your camera has one, or use a magnifying eyepiece if available.
Shoot more than one frame, refocusing each time, because even if focus is “accurate,” perceptual effects change with very small differences in focus. Field curvature, where the image sharpness does not fall in a geometric plane, causes some areas of the subject to be unexpectedly blurred or sharp relative to other areas at the same distance, another reason to focus-bracket.
Bokeh and Color Bokeh
Bokeh is the way an image blurs when out of focus. With most lenses, bokeh is pleasing, but some lenses can produce distracting shapes with harsh transitions that attract unwanted attention. The bokeh of a lens can be a key factor in choosing it for any particular subject.
Color bokeh leads to magenta/green bands of color on out of focus areas, caused by insufficient correction of color errors, and includes lateral and axial chromatic aberration and spherochromaticism. Axial chromatic aberration is visible as violet or purple fringing around bright points and is due to poor correction in the near-ultraviolet range. Color bokeh can figure into the overall gestalt of some images.
A wide aperture lens is a creative tool that can make compelling landscape images distinctly different from convention. Try a variety of lenses to see what appeals to you.
Product Resources: Cameras: Leica M9 with Leica 1.25 X magnifying eyepiece, Nikon D3x, Canon 5D Mark II, Lenses: Leica 50mm f/0.95 Noctilux-M ASPH, Nikon AF-S 24mm f/1.4G, Zeiss 35mm f/1.4 Distagon; Filters: B+W 2-stops, 3-stop and 6-stop neutral density; Tripod: Gitzo GT 3541 XLS; Arca Swiss Cube tripod head; Memory: SanDisk 32GB Extreme III SDHC card, SanDisk 32 Extreme Compact Flash card; Software: Adobe Photoshop CS5, Nikon Capture NX2; Other: OpTech Pro Loop strap.