Posts Tagged ‘composing photographs’

Sharpen Your Shots And Come Out Winning

Monday, September 9th, 2013

mcShaking a tripod-mounted camera is a common problem. A cable release prevents the transfer of movement from the shutter finger to the camera body because the shutter is tripped by the release. Mechanical releases screw into the threaded shutter-release button while electronic ones fit into a separate socket. Both types should have an option to lock the shutter open for time exposures. Alternative ways to trip the shutter while keeping the camera steady are by using the self-timer or a remote cable release. The self-timer allows for sharper images because the movement dissipates prior to the shutter opening. A remote release triggered by radio or infrared waves can also trip the shutter button.

Mirror Lock-up

This is a feature I wouldn’t be without. Much of the work I do is either with macro or long lenses. Both greatly magnify the subject, but as magnification increases, so can poor technique. Specific apertures often necessitate shutter speeds between 1/4 and 1/30. These speeds are notorious for causing cameras to vibrate because of mirror “slap.” By locking the mirror in the “up” position, this is eliminated, keeping the camera steady during the exposure.

When you release a camera’s shutter, the mirror flips up and then returns to its set position. This movement–be it ever so slight–sets the camera in motion, causing the image to lose sharpness. Shutter speeds shorter than 1/30 and longer than 1/4 aren’t affected as much because of the brief ratio of time in which the motion occurs, as opposed to the amount of time the shutter is open.

Don’t despair if your camera doesn’t have mirror lock-up. There are still ways to increase the chances of getting sharper pictures (Intenscreen can help). Pressing down on the lens barrel with your hand adds stability by stifling the movement of the tripod-mounted camera. Another alternative is to hang your camera bag over the lens barrel. Just make sure the ball head is fully tightened.

Filters

Filters are great assets to photographers, yet they can also be a nemesis. They’re susceptible to fingerprints, smudges, dirt and dust. Before every shoot, it’s a good idea to do a thorough cleaning of both sides of the filter you plan to use. Microfiber cloths or lens-cleaning tissues with lens-cleaning solution work well. You should use canned air or a soft brush before rubbing the surface clean to prevent any dirt or sand particles from scratching the filter.

We photographers sometimes spend hundreds of dollars on a lens, yet we may try to save a few bucks by buying a cheap filter. Cheap glass translates to fuzzy photos and increased chances of flare. Don’t skimp on filters–budget good ones into the price of your lens.

Film Speed

Film speed has a direct impact on the final enlargement’s sharpness. The general rule is the slower the ISO, the sharper the film. Hence, you can make bigger enlargements from lower-speed films. However, the caveat is the slower the film, the more careful the photographer needs to be about eliminating camera shake or controlling depth of field.

Films in the ISO 25-100 range are extremely sharp and have very fine grain. This translates to sharp enlargements of 16×20, and even 20×24, from 35mm film. When using these emulsions, tripods are essential, along with other appropriate camera-handling techniques. Films in the ISO 200-400 range rival the slower emulsions of only a decade ago. These films are great to use when hand-holding your camera is necessary, and they produce nice prints up to 11×14. Faster emulsions are reserved for low-light conditions. Enlargements made from these emulsions begin to reveal much more grain and are not as sharp. But if your goal is to produce 5x7s or smaller, these films are wonderful. Don’t expect to shoot an ISO 1000 film and have it compete in grain structure and sharpness to Velvia or Kodachrome 25. My best advice is to use the slowest possible film for the subject’s action and lighting conditions.

Lens Choices

All lenses have a “sweet” spot at which the highest resolution and edge-to-edge sharpness occur. Typically this is when the lens is set at f/8 or f/ll. Most lenses tend to be their sharpest when stopped down two to three stops from their widest opening. The exception is a macro lens: they’re manufactured to be at their sharpest when fully stopped down, as most macro photography dictates small apertures to maintain depth of field.

With lenses other than macro models, some photographers recommend avoiding apertures of f/22 or f/32 because diffraction becomes a problem. Since much of my scenic work requires foreground-to-background sharpness, I religiously ignore this “rule.” For me, it’s critical to have everything in focus in my picture, and not worry about a small amount of diffraction. Today’s high end lenses are of such high quality that the diffraction factor is barely detectible.

Critical focusing is very important when wide-open apertures are used. With today’s autofocus technology the problem is minimized, but I still find myself using manual focus quite often. I use the focus-assist arrows and lights in the viewfinder, but I often fine-tune the focus to get critical sharpness. Be sure to test all your lenses for focusing accuracy. My 75-300mm lens is definitely sharper when I tweak it, rather than when it indicates that it’s dead-on using autofocus.

Focusing on key parts of the subject and making sure these areas are tack sharp implies greater sharpness. For instance, when photographing people, it’s essential that the eyes are the crispest part of the picture. A photo of a person with a sharp nose but soft eyes fails as a successful image, but sharply focused eyes with a soft nose is acceptable.

The lens quality impacts the quality of the photo–there is no “free lunch.” The more you pay, the better the lens. Those with designations like APO, ED, and L signify the inclusion of high-quality glass elements that increase sharpness throughout the full aperture range, and decrease flaws such as aberrations, coma and astigmatism. These lenses often have elements made of fluorite and other special glass that helps eliminate diffraction and other sharpness-reducing phenomena.

Shutter Speed

When photographing stationary subjects like mountains and buildings, action-freezing shutter speeds aren’t mandatory. But if the subject demonstrates even slight movement, like a flower swaying in a gentle breeze, a poorly chosen shutter speed can ruin the photo. The faster the action, the higher the shutter speed necessary to freeze it. Additionally, the angle at which the subject is moving requires different shutter speeds to freeze it. Action coming toward or moving away from the camera can be frozen with a slower shutter than action at the same speed moving across the film plane.

If you want to freeze the action of a wide receiver snatching a football in midair by using a shutter speed of 1/1000 or faster, then medium-speed film, a fast lens and sunlight are all necessary to capture this frozen moment in time. This reveals an obvious rule of thumb: freezing the action is directly related to the speed of the motion offset by the film speed, the widest aperture of the lens, and the amount of light falling on the subject.

Electronic flash can create action-stopping, razor-sharp photos. Even though most camera’s flashes sync between 1/60 and 1/250, the duration of the flash that illuminates the subject ranges from 1/1000 to 1/50,000. Because of this, a hummingbird’s wings can be frozen in time. But flash has limitations in stopping action, especially when it comes to flash-to-subject distance. When seated in a stadium, don’t expect flash to freeze the action on the field.

Depth of Field

lpAs you stop down a lens from f/4 to f/22, the range of sharpness increases. This creates tremendous impact in separating the main subject from the background. In portraiture, it’s common to use long lenses at wide-open apertures. The subject stands out from a blurred background, making the subject appear tack sharp. Conversely, in landscape photography, an image is more successful when everything from the foreground to the background is in focus. This often dictates the use of wide-angle lenses with apertures of f/122 or smaller.

Minimizing depth of field is simple. Choose the longest lens suitable for the shoot, set it at its widest aperture, and position the subject in a location so you can focus the lens at its closest point. For greater depth of field, begin by stopping the lens down to a smaller aperture, use a wider-angle lens, or move farther away from the subject.

Maximizing depth of field requires more understanding. Getting the greatest depth of field depends on where the point of focus is in a scene. Focusing about a third of the way into the scene gives the greatest focusing range, since depth of field is maximized with approximately 1/3 sharp focus falling in front of the subject, with falling behind. This is known as the hyperfocal distance. There are commercial charts available that indicate hyperfocal settings for many focal-length lenses.

Another way to increase apparent sharpness is to make sure the subject is parallel to the film plane. Let’s say that a butterfly with open wings fills the frame. The ambient light indicates an aperture of f/8. Someone is next to you and directly above the butterfly with a camera parallel to its wings. Your camera gear is set up at your friend’s side. Your friend gets wing to wing sharpness because his/her film plane is parallel to the butterfly. Because you’re shooting the butterfly from an angle, parts of the wings will be sharp while other sections are soft. The larger the f-stop, the more apparent this becomes.

Image-Stabilizing Lenses

Lens stabilization technology is resulting in a greater number of sharp images. A rule of thumb dictates that you should never hand-hold a lens at a shutter speed that’s slower than the reciprocal of its focal length. For example, a 200 mm lens should only be handheld at a shutter speed of 1/200 or faster. Image stabilization reduces that number up to three shutter speed settings. Therefore, a 500 mm lens can be handheld at 1/60 and still deliver a sharp image.

High Magnification

When working with magnification–whether it’s macro or telephoto–you must use careful camera-handling techniques to decrease the number of throwaway images. Camera vibration is a problem, as is narrow depth of field. The means by which the image is magnified is also thrown into the recipe.

Camera vibration can be eliminated first by using a sturdy tripod. With high magnification, depth of field can be as narrow as a few millimeters, so accurate focusing is critical. In telephoto work, autofocusing is a great asset. I make sure one of the autofocus sensors is placed over the exact spot I want sharp, then I recompose the image with the focus locked. If the focus isn’t locked, the focusing point will change when I recompose the shot. For macro work, I have an attachment that fits over the eyepiece to manify what I’m photographing.

To get a longer reach out of a telephoto lens, you can use a teleconverter: the most common of these are 1.4X and 2X. These converters vary in quality and are often matched to a given focal length. Better-quality converters tend to be pricey, but are much cheaper than buying a longer focal-length lens. For macro work, I suggest you stay away from close-up filters unless they’re the two-element, high-end types.

Telephoto lenses present an additional problem. The long distance between the camera and subject means shooting through large expanses of air that can be filled with moisture, pollutants, dirt and dust. All of these degrade the image by lowering the contrast impacting sharpness. In hot areas, the shimmer radiating from the ground has the same effect. If possible, get closer to the subject.

Finally, differing types of light affect apparent sharpness. Contrasty, harsh, or directional light is sharper than light that’s soft, lacks shadows, or comes from the front. A wider tonal range exists between the shadow and highlight areas with contrasty light, so the areas between these sections appear sharper. Conversely, when the contrast range is lower or the subject is lit from the front, the area appears flatter in tone.

Because contrast conveys sharpness, many printers prefer glossy paper. This is especially true of negatives shot in fog or on overcast days. “Snappy” is a term often used when describing why glossy paper appears sharper.

Wrap-Up

Make your picture-taking more rewarding. Don’t say, “I wish I had used a tripod for that shot.” Simply use it. Don’t say, “I should have changed rolls and used a faster ISO.” Next time, do it! Incorporate the techniques on these pages that will net sharper images into your repertoire.