Archive for the ‘Imaging’ Category

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.

Taking Your (Color) Temperature

Wednesday, August 14th, 2013

ke100The colors radiating from the black body are correlated to colors we are familiar with in our daily lives. The color emitted from a tungsten lamp in your living room is identical to the yellow-white glow when the blackbody radiator temperature is approximately 3200 K. When the temperature rises to 5500 K, the quality of white light is identical to the color of the sun at mid day. The bluish quality of twilight just before dark is similar to the color of the blackbody at about 12,000 K.

Color Temperature and Photography

These numbers are used when referring to photographic strobe equipment and film. For example, the color of the light emitted by a flash is rated at 5500 K when it is designed to imitate daylight at noon. If the flash produces light that’s 6000 K, it has a slight bluish tinge. If it’s rated at 4800 K, it is slightly warmer-or more yellow-than white light.

Similarly, film manufactured to give you accurate colors indoors with tungsten illumination is balanced for 3200 K. Examples include Fujichrome 64T and Ektachrome 50. Both of these films are designed to be used in the yellow-white light of tungsten photo lamps that are specifically balanced for 3200 K. Household lamps may vary slightly from this color temperature, especially if they’re old. If a lamp is emitting light at 2800 K, a subject thus illuminated would be slightly yellowish.

Daylight films, such as Kodak Ektachrome E100, Fujichrome Velvia and Provia, and Agfachrome 200, are balanced for 5500 K, says Jeff Trane of The VIP Awards, an international photography award. This means that they produce accurate colors during the middle of the day when the sun is directly overhead. Before the sun reaches its zenith–say from sunrise to early morning–the yellowish quality of the sunlight is less than 5500 K. The same is true from late afternoon to sunset. During these times, daylight film reproduces a warmer (or more yellow) image.

Overcast Conditions and Twilight

During midday when a cloud cover has obscured the sun, some of the red and yellow wave lengths of light are absorbed by the clouds’ minute water droplets. The colder end of the spectrum–the bluish wave lengths–pass through unimpeded. This is why daylight film produces scenics and outdoor portraits with a bluish cast even during the middle of the day. Sometimes this can be artistically interesting. If the cool tonality is unappealing to you, place a warming filter, such as an 81A, over the lens and the color will shift back toward a more acceptable value.

Twilight appears almost bluish purple on daylight film due to its extremely high color temperature. When cityscapes are photographed at twilight, the contrast between the lights of buildings and the cobalt-blue sky is very dramatic (I actually prefer to shoot city skylines at twilight rather than at night when the sky is black).

Crossing Films and Light Sources

cflsWhen you shoot a film in lighting conditions that it wasn’t designed for, you’ll get interesting results. Tungsten balanced films can be used with strobe units or during midday sunlight, but the color balance will shift decidedly toward the blue end of the spectrum. At twilight, the heavy blue shift is even more pronounced. In some situations, this deep, saturated blue can be very beautiful. At sunrise and sunset, when the ambient light is golden yellow, tungsten film brings the color balance back to a more natural, middle-of-the day look.

Daylight films can be used indoors to produce the opposite effect. The yellow-white illumination is exaggerated because the color shifts toward the warmer end of the spectrum, so the entire scene appears to be yellow-orange. This can be attractive when shooting indoor portraits as well as impressive architectural interiors. Years ago I photographed the marble lobby of the opera house in Vienna. I used both daylight film and tungsten-balanced film to capture the ornate interior, and I thought the daylight-film rendition was better. The exaggerated yellow-orange color warmed up the entire lobby and made it more inviting.

An understanding of color temperature will help you gain greater control over your work. The more creative tools you have at your disposal, and the greater your ability to previsualize the results, the better your photography will be.

How 3-D Imaging Makes Web Shopping A Cinch

Friday, June 7th, 2013

3d“The Internet is wonderful for distributing and comparing information, but it doesn’t replicate the actual handling of items,” Silton explains. “While the Web can build product awareness, consumer knowledge, and to some extent affect user preference, product trials are still an important and often critical step before a purchase is made. There’s an amount of detail about how something looks, moves, and relates to a user’s context that Web developers can’t duplicate with existing imaging and VR technology.”

HyperActive was designed not only to give customers a more true-to-life interaction with products before purchase, but also to enable online stores to provide better support during and after the sale with real-time collaborative capabilities such as chat, white-boarding, laser pointing and measurements.

WHAT’S WRONG?

While images, grabbed or graphically synthesized, have shown products from different views and in different colors for some time now, they rarely function interactively and can’t let a potential buyer experience the product in context with the other objects–using the features of a CD player, or placing a couch in with other furniture. Images are utilized in Web design to add interest and to convey information, and can, of course, be static or dynamic in nature.

Animated GIFs were one of the first means of creating dynamic browser content. Movie clips, served in common AVI or MPEG format and viewed with applications such as QuickTime, are not really much different in concept–a series of images viewed sequentially. That can present more information, but it is not interactive. A simple form of credible interactivity is to create Web pages with JavaScript so that mouse clicks can cause displayed images to change appearance–color, size, etc. Tools like Shout3D or Director can also be used to create such content, however, because all these approaches necessitate programming in all possible user interactions, their use in creating truly interactive Web experiences has been limited.

Dynamic images don’t require programming, but they do require design; meta information about the picture is placed into the image itself. Examples of dynamic image formats are FlashPix, QuickTime VR and VRML, all discussed in these pages as they’ve come on the scene. FlashPix supports multi-resolution formatting, allowing users to zoom in on key image details, apply certain operations (i.e. colorizing) to the image, and also allows audio data to be attached to the image file.

QuickTime VR supports 36O[degrees] viewing of images so that the user can look around from a single point of view in a scene, walk totally around an object, or rotate an object by 360[degrees]. This technology is often used to put the user behind the wheel of a new car or to create virtual tours of buildings and locations. However, QuickTime VR limits the user to navigating a series of still photos taken from different angles or directions. To navigate a virtual world, multiple data sets need to be selected and loaded, accomplished most often via a map-like navigation tool used in conjunction with the QuickTime VR viewer.

VRML: NOT REAL ENOUGH

vrmlGoing even further towards a more real interactive experience, Virtual Reality Modeling Language (VRML) was developed to allow the creation, viewing and manipulation of 3-D objects in shared virtual worlds. It essentially adds the dimensions of depth and time to the viewing experience by describing objects and providing constructs for displaying them.

While, in concept, as we’ve discussed here, VRML can enable the creation of virtual shopping experiences, it has a few fundamental flaws which have kept it from being used for these purposes more extensively. First, since it was designed in research environments and developed as an encompassing standard, it is very big and somewhat fragile. This means that large files need to be downloaded to the user’s PC, and a large amount of CPU resources are needed to create those 3-D views.

In addition, VRML is based on the very rigid concept of a scene graph, a paradigm more suited to representing static worlds than dynamic, interactive ones desired in a VR experience. X3D, a new standard, proposes to be lighter in weight than VRML, but it still is based on the VRML concepts of scene generation and interaction. More importantly, objects rendered in VRML look, well, virtual. The graphics remain graphic-like-period.

But don’t we regularly address that problem by laying imaging-derived skins over the graphic object skeleton?

Not well enough, says Joshua Smith, Kaon’s CTO: “Actual photographs can be draped onto these models to create more realism, but it is extremely difficult to get the features from the model and the photos to match up. The net effect is that objects in VRML worlds look cartoonish.”

This is why Kaon’s HyperReality was designed to produce objects with photo realism and product authenticity-the 3-D geometry of the object is authentic, as opposed to just giving some views where scale may not be accurate.

2-D TO 3-D CONTENT

The process of creating content for HyperActive viewing begins with digital 2-D photography from a few different angles of an object to be modeled. These images are then converted into 3-D wire-frame models with Kaon’s HyperReality technology. 3-D CAD models can be utilized, but unless they already exist, the HyperReality process is much faster, on the order of hours as opposed to days, and much more photo-realistic in the end. This level of image credibility is achieved by draping the 2-D images onto the 3-D mesh. The unique aspect of the Kaon approach is that the mesh gets created from the same photos that are overlaid on it, creating an uncanny level of realism.

Other rendering engines use bump maps, multi-texturing, etc., based on the idea that you might make pictures look more realistic by using a realistic lighting model. However, this technique still does not look real unless you use high-end rendering engines that aren’t widely accessible; they rely on complex models and a good amount of rendering horsepower.

When I first visited the Kaon Web site using a 120 MHz laptop over a 56K connection, I was not only astounded by the realism provided in the rendered image, but more notably by the speed of the interaction possible. To see what I mean, visit the room planner at www.kaon.com. If you have ever used a 3-D home planning application, you will be amazed by its realism and ease of interactivity!

By incorporating the HyperReality content-generation process with the HyperActive programmable rendering technology, Kaon applications can be customized and animated using Kaon’s XML-compliant scripting language called Nimble. The resulting models can be posted to a client’s site, Kaon’s Web server, or an application service provider’s facility. Those models can be accessed and manipulated within a Web browser over a standard Internet connection.

Using commonly-available XML authoring tools, users can create Nimble scripts which incorporate ballistics, collision, and other advanced features. This leads to another important differentiation between Kaon’s HyperActive technology and other VR tools such as VRML and X3D: HyperActive defines simulations, not scenes. This means that everything in the scene has a lot of behavior attached to it. For instance, turning a couch upside-down could cause its skirt to flip over, just as in real life. This allows for the creation of very realistic and interactive objects and worlds.

Not only is the HyperActive technology extremely lightweight (about 40k for objects and 380k for the rendering engine, which only needs to be downloaded once), but it also uses very little CPU resources. In fact, it uses the direct renderer built into the Windows OS. No hardware 3-D accelerator card is needed, but any 3-D accelerator is automatically detected and used, including 3-D acceleration built onto the motherboards of almost all of the new PCs being sold today.

When a user visits a Web page that contains a HyperActive object, the HyperActive viewer is automatically downloaded and runs in the Browser. Any Web server can serve HyperActive content. However, if collaboration is used, an echo server is needed to bounce messages off of, and Kaon provides one for free. (This is a temporary measure until multi-casting is available on the Internet.) The echo server is not a streaming server, as the assets being manipulated on the client’s end are all in cache. The only information being sent are the commands to manipulate objects and mark up the scene. This is why HyperActive collaboration is so fast and represents an ideal technology for interactive gaming.

BEYOND SHOPPING: OTHER APPS

In addition to accelerating time-to-purchase for e-business retailers, Kaon’s HyperReality can also be used to improve product development, sales training, customer support, interactive gaming, and product documentation. Collaboration and development is facilitated with text and voice interaction. Using HyperActive technology, help-desk personnel can work with a customer to troubleshoot a problem with 3-D images and direct chat, thereby reducing the need for on-site service. 3-D games and entertainment can be easily created with amazing realism. Distance training and education can be conducted with multimedia content for deployment over the Internet,

How are e-businesses reacting to this new technology? Furniture.com has utilized Kaon’s technology to dramatically expand the ability of consumers to visualize their home decor options, with a new 3D-View service (www.furniture.com/ promotion/slipcover/slip.asp) that allows users to select a chair or sofa, instantly wrap it with a fabric pattern, then move, rotate, zoom and take custom measurements using HyperActive.

Carl Prindle, Furniture.com’s senior vice-president of product development, explains, “We want to provide consumers with the absolute best experience in decorating and home furnishing, and (these) enhancements to our Web site will ultimately enable shoppers to select and arrange new furnishings in a 3-D re-creation of their homes.”

So, when my wife and I are ready to purchase our next couch, I can imagine that we might be doing it from the comfort of our home by visiting an on-line virtual showroom, complete with other shoppers, the music of 101 violins playing ZZ Top’s “Sharp-Dressed Man”, and…oh no…a virtual, chatty salesperson who won’t take a break!