Canon Image Stabilized EF-S Lenses

Canon's latest lenses incorporate its Image Stabilizer technology while maintaining a compact design. This superior technology allows excellent low-light digital photography as well as longer shutter speeds. The EF-S 55-250mm f/4-5.6 IS Telephoto Zoom Lens was awarded the Best Entry-Level Camera Lens by the Technical Image Press Association (TIPA) for 2008.

Amstelveen, The Netherlands, 20 August, 2007: Canon today strengthens its EF-S series of lenses with the launch of the EF-S 18-55mm f/3.5-5.6 IS and EF-S 55-250mm f/4-5.6 IS. With equivalent focal lengths of 29-88mm and 88-400mm respectively, the lenses are the first in the EF-S series to incorporate a 4-stop Image Stabilizer, dramatically extending low-light performance. Both lenses incorporate specialist optics to achieve exceptional image clarity - the EF-S 18-55mm f/3.5-5.6 IS employing an aspherical lens element with the EF-S 55-250mm f/4-5.6 IS benefiting from an Ultra-Low Dispersion (UD) lens element.
The lenses are built to fit exclusively on those EOS cameras with an EF–S lens mount – including the new EOS 40D, EOS 30D, EOS 400D and earlier models.

EF-S 18-55mm f/3.5-5.6 IS Camera Lens

The Canon EF-S 18-55mm f/3.5-5.6 IS digital camera zoom lens is a lightweight general-purpose lens that is ideal for handheld photography in a wide range of lighting conditions. Offering high optical quality, the lens has an 11 element, 9 group construction, including one aspherical element for crisp corner-to-corner detail. The lens maintains a closest focusing distance of just 25cm throughout the zoom range, giving photographs the flexibility to frame up close when needed.

EF-S 55-250mm f/4-5.6 IS Camera Lens

Compact and lightweight, the Canon EF-S 55-250mm f/4-5.6 IS digital camera zoom lens offers the longest zoom range in the EF-S series to date. The 88-400mm equivalent focal length opens up new framing possibilities for owners of EF-S mount cameras shooting wildlife, sports and travel photography. Optical quality is assured through a UD element, which minimizes chromatic aberrations that could otherwise cause reduced contrast and color fringing.

4-stop Image Stabilizer

Canon’s latest optical Image Stabilizer (IS) technology provides up to 4-stop compensation for image blur caused by camera shake and slow shutter speeds. Photographers normally shooting handheld at 1/250 sec can switch on IS to obtain a similarly steady and blur-free result with a shutter speed of just 1/15 second. The inclusion of automatic panning detection makes it easier for photographers to track wildlife and other moving subjects. To ensure consistently accurate results at all zoom positions, the IS system within each lens has been optimized for that lens’ specific focal length range. Since the IS system is based within the lens, the results are visible through the viewfinder when framing the image.

Appealing background blur

Both lenses also incorporate a circular aperture. This helps create an even background blur when depth of field is minimized, giving photographers more creative options for portraiture and similar types of photography.

Super Spectra coatings

Both models employ Canon’s patented Super Spectra coatings to suppress flare and ghosting – more prone to occur with digital cameras due to reflection off the image sensor. By increasing light absorption, coatings reduce reflections off lens element surfaces to deliver crisp, undistorted images with natural color balance.

E-TTL II flash integration

The lenses transmit distance information to the E-TTL II flash system of all current model digital EOS cameras, improving flash exposure metering when used in conjunction with Canon’s range of EX Speedlite flash units.

In keeping with Canon’s Kyosei philosophy of living in harmony with the environment, the lens features only lead-free glass.

Using Long Lenses in Digital Photography

Great digital photographs can result from using a telephoto lens to get in close to the action or sneak up on a subject from a discreet distance. But the high magnification of long tele and zoom lenses serves to accentuate the effects of camera shake caused by your inability to hold the camera and lens absolutely still. The effects of wind, moving or shaking floors, residual vibration from camera mirrors flipping up just prior to exposure, atmospheric haze, and heat waves can also add problems.

When hand-holding your digital camera and zoom lens, start with a fast film, ISO 400 or higher. This will allow you to use higher shutter speeds (1/1000 sec and above) and minimize the effects of shake in a variety of lighting conditions. Use the proper stance: arms closely tucked into the body, elbows partially supported by the chest or abdomen, lens and camera balanced by the left hand and arm.

Practice supporting and focusing the digital camera with your left hand. Aim the digital camera slightly above the subject, take a deep breath, let the view drop to the proper composition while exhaling, and gently press the shutter.

For support, find a fence post, parked car, or folded jacket. Lean on it or rest your digital camera on top of it while shooting. If you have such a support, a 1/30 second exposure isn't an impossibility, even with a 500mm lens. You'll be using slower shutter speeds more often than you'd like. The minimum shutter speed rule of thumb for hand-holding a long tele or zoom lens is this: Slowest safe shutter speed = 1 over the lens focal length.

For example, if you're photographing with a 500mm f/4 lens, the limiting shutter speed for a hand-held digital photo would be 1 /500 second at the correct aperture for a good exposure. This rule applies to a properly-braced photographer standing on solid ground.

Chest braces, rifle stocks, and similar devices aren't as practical as a lightweight monopod or tripod. A monopod is easy to carry, and you can set it up just about anywhere.

It won't allow you to set shutter speeds as slow as you can get away with using a tripod. But it will let you shoot safely—that is, without a serous risk of image-softening shake—at speeds two or three steps slower than you'd have to use if you were shooting handheld. That may make it possible to shoot in lower light, and/or to use a slower, finer-grained film.

Get a monopod that can be raised to your eye level, is quick and easy to set up. If you shoot a lot of verticals, you may want to add a good swivel ball head for maneuverability.

A tripod is the best device for insuring minimal effects from vibration with a long tele or zoom lens. With a sturdy one, you can use slower shutter speeds and lower ISO-higher resolution films. If you own a shaky tripod, tie a three to five pound weight to the center column for added stability.

Physically long tele-lenses should have tripod-mounting collars to attach the lens at the proper fulcrum to the tripod rather than the digital camera. You can also use a secondary support for the digital camera like Bogen's Long Lens Support. This telescoping brace attaches to most tripod legs via a universal clamp at one end and a swivel ball head for the digital camera at the other. The brace makes it more difficult to change camera position, but it considerably lessens the effects of vibration.

If you're on shaky ground, tripods won't help. They'll actually transmit the motion right to the lens and camera. It's better to handhold the camera if you can set a reasonable shutter speed, and let your body damp the vibration.

Atmospheric haze and heat waves can't always be eliminated, but using a haze or polarizing filter can help cut through the haze and increase color saturation and contrast. Also, use your lens hood, or shade the lens, to minimize the possibility of flare.

Few techniques in photography require more expertise and skill than the successful use of a long tele or zoom lens. If you want to become more proficient, practice, practice, practice!


About the Author: Jan Linden is a professional photographer and designer.

Digital SLR Cameras - Body and Lenses

By: Jacob Georgeson

Digital SLR cameras are usually sold in two parts: the camera body and lenses. There are many types of lenses with different characteristics from macro to zoom, with special options like image stabilizers, special filters and more. In this article you will read about some lenses options and what you should consider when buying them.

You can and should own more than one lens. Different lenses are better at different scenes. An obvious example is the difference between a macro lens used to take shots of objects from a very short distance sometimes almost touching the camera and zoom lenses designed to take photos from a far distance. Professional photographer always carry a few lenses with them and change the lens often in order to use the right one for each photo shot. Sometimes professional photographer actually carry a few cameras with different lenses mounted on them allowing them to quickly choose the perfect lens for each shot without the need to actually switch lenses back and forth.

Some lenses also provide special features that better the photos taken. For example, image stabilization, also known for short as IS, eliminates the effect of small camera movements as the pictures is taken. Such movements are a problem in extreme cases for example when shutter speed is low in low light scenes or when using a high zoom lens taking photos from far away. In those cases every small camera movement translates to blurry digital photos. The image stabilizer (IS) is an optical electro-mechanical mechanism. Using a gyro and a floating optical element the image stabilizer senses camera movements and moves the optical element in right direction and distance to compensate for such movements.

If you need to take photos of objects from a very short distance you should consider purchasing macro lenses. Macro lenses enable the digital camera to be positioned very close to the object sometimes almost touching the object and still sharply focus on it. Common objects that photographers experiment with when using macro lenses are insects, leaves, screws, nails, bolts and more. Another challenge with macro photography is lighting. If you need to use a flash any normal flash would emit light that is too intense just because the object is closer to the camera than the focus was designed for. You can either use a flash that allows setting for such a distance or place a filter on the lens.

If you plan to use really long zoom lenses you should consider lenses that support special tripod mounts. Cameras with very long lenses are heavy and their gravity center shifts out toward the lens. In order to stabilize a camera with such lenses a special tripod attached to the lens is needed. When buying such lenses it is recommended to make sure that such a tripod can be used with the lens and if you already own a tripod that the mounting mechanism is compatible with the lens.

When buying lenses you should also take into consideration their planned usage. Tow lenses can have the same optical characteristics but for example very different weights just because they are made from different materials. If you plan to travel and carry the lens weight is important even at the cost of a higher lens price.


Author: Jacob Georgeson is digital cameras expert.

Article source: Articlecat.com

Photography Zoom Lens Characteristics

By: Jennifer Clarkson

When you own a Single Lens Reflex (SLR) camera, you have the option of purchasing more than one lens for various purposes. This article explores some characteristics you should consider once you've decided on the type of zoom lens you plan to purchase, including Internal Focusing, Image Stabilization or Vibration Reduction, Constant vs Variable Aperture, Macro Focusing, Low-Dispersion Glass, Apochromatic Lenses, Aspherical Elements, Tripod Mounts for Long Lenses, Plastic vs Alloys, Size, Weight, and Price. For more information on the different types of photography zoom lens available, read this article.

Internal Focusing (IF)
The movement of the lens for focusing purposes is internal to the lens body, so no lens ring will cause the lens to twist out and interfere with the orientation of any filters. (Some filters, such as linear polarizers or graduated neutral-density filters require stationary positioning in order to deliver predictable results.) This internal movement also allows the lens weight to stay balanced, which helps the balancing of heavier lenses on a tripod. Image quality of newer IF lenses is slightly better than non-IF lenses due to technological advances made that correct some aberrations.

Image Stabilization (IS) or Vibration Reduction (VR)
Most types of lenses above come in two flavours: either with image stabilization, or without. Built-in stabilization allows you to get sharp hand-held images when lighting conditions are poor, or you're shooting from a moving vehicle. On the lenses that offer this capability, there is usually a switch that lets you turn the feature off, thus saving batteries when using a tripod. Beware the cost of these lenses, though: you can expect to pay 2-4 times as much for a lens with image stabilization than the same lens without.

Constant vs Variable Aperture
Variable aperture accounts for the majority of zoom lenses, and causes the maximum aperture to decrease as you zoom from wider focal lengths to telephoto focal lengths. The advantage of variable aperture zoom lenses is that they're cheaper to maufacture and are typically lighter and more compact than contact aperture lenses.

Constant aperture lenses provide a static maximum aperture regardless of the focal length you're zoomed to. This better enables you to achieve narrow depth of field so as to isolate your subject from your background. These lenses typically let more light in, which lets you shoot sharp photos in dimmer lighting conditions.

Macro Focusing
Macro lenses allow the camera to be very close to its subject and still focus sharply. Macro lenses are ideal for close-up shots of flowers, leaves or insects, and sometimes double as portrait lenses. They typically have a reproduction ratio of 1:4 or better, which means the image sensor will capture the subject at 1/4 its original size or larger.

Low-Dispersion Glass
Some lenses are made with high-quality glass specially manufactured to more accurately transmit the full visible colour spectrum, called low-dispersion glass. You may also hear of ED (extra-low dispersion), SLD (super-low dispersion) or UD (ultra-low dispersion), which really just means truer colours.

Apochromatic Lenses (APO)
Apochromatic lenses have high colour fidelity and sharpness and should be used by anyone obsessed with getting to the most accurate colours possible.

Aspherical Elements (ASP)
Aspherical lenses are made with a different curvature than traditional spherical lenses to correct for distortions at the edge of the image. They are particularly useful in wide-angle lenses where vignetting or distortion can be seen in the corners of the image.

Tripod Mounts for Long Lenses
Lenses that are bigger and heavier than your camera body should have a tripod mount built-in. By attaching the lens to the tripod instead of the camera, you will remove tension on the camera-to-lens mount joint, and you will improve tripod balancing in the field. In fact, without a tripod mount, some larger lenses will cause the tripod to topple, thus making tripod use impossible without a lens mount. It is possible to purchase a separate adapter bracket from some manufacturers if the lens itself does not have one.

Plastic Material vs Alloys
Plastic lenses built recently typically use high-tech materials that are very durable and much lighter than metal alloy lenses. So although it used to be said that plastic lenses are cheap and unreliable, that is no longer true today.

Size
Zoom and telephoto lenses are getting smaller and lighter each year. In general, the larger the focal length of the lens, the larger the lens will be physically.

Weight
The heaviness of a lens may be prohibitive to you, depending on your physical fitness level and how long you'll be away from home. Plastic lenses are quite durable and are definitely lighter than equivalent metal lenses, although ultra-lightweight metal alloys are reasonable as well.

Price
In general, no matter which lens you're looking at, prices vary dramatically based on lens quality. Professional lenses will cost you thousands of dollars, while a compact modest starter zoom lens will be only a hundred dollars. You'll pay extra for some of the characteristics discussed in this article, such as fast constant apertures, high quality glass, image stabilization, and quick auto-focus. Remember, though, that lens price is a large investment: lenses will long outlast your camera body, and is largely responsible for the quality of your images (much more so than the camera body itself)!


Author: Jennifer Clarkson is a Canadian photographer living in Ottawa. For more Photography Tips, or to view her Photo Gallery, please visit Jennifer Clarkson Photography.

Article source: Articlecat.com

Zoom Lenses for your SLR camera

By: Jennifer Clarkson

When you own a Single Lens Reflex (SLR) camera, you have the option of purchasing more than one lens for various purposes. Zoom lenses and prime lenses are something that every SLR owner should have. Let's look at the definition for each.

Prime lenses are those with a fixed focal length, such that zoom is not possible. That means that if you wanted to have your subject appear larger in your frame, you would have to physically move your camera closer to the subject instead of zooming closer with the lens itself. Prime lenses are faster at focusing than zoom lenses, but are typically used for static scenes, such as macro photography or portrait photography.

Zoom lenses allow you to make your subject larger in the frame without physically moving your camera closer. This article explores the different types of zoom lenses out there and offers recommendations for what suits your style of photography - macro, landscape, wildlife, sports. We'll look at autofocusing zoom lenses and manual focus zoom lenses. Also check out this related article about Camera Lens Characteristics.

Autofocusing Zoom Lenses

1) Ultra Wide-Angle Zoom Lens

Typical focal lengths: some range between 17-35mm (e.g. 20-35mm, 17-28mm, 17-35mm)
Characteristics: The angle of view is quite wide, around 170 degrees from the camera. The depth of field is large, so foreground and background will be in sharp focus all at once.
Uses: landscape photography

2) Wide-Angle To Moderate Telephoto Zoom Lens
Typical focal lengths: some range between 24-105mm (e.g. 24-85mm, 28-105mm, 35-80mm)
Characteristics: Typically the first type of lens you purchase with your SLR. These lenses provide the range needed for most shooting situations, aside from specialty photography. Their weight is light, and their size is compact, so these are usually the easiest lenses to travel with when you only want to take one lens.
Uses: travel photography, landscape photography

3) Mid-Range Telephoto Zoom Lens
Typical focal lengths: some range between 50-300mm (e.g. 70-200mm)
Characteristics: These lenses are slightly larger than the category above, but are still fairly compact. They are better for photographers who typically want a telephoto shot from a distance. They best compliment a wide-angle zoom and a telephoto zoom together to cover most focal lengths.
Uses: wildlife photography

4) Telephoto Zoom Lens
Typical focal lengths: some range between 100-300mm (e.g. 70-200mm)
Characteristics: These lenses offer high magnification, allowing you to get up close to dangerous or distant subjects while keeping your distance. Depth of field can be small with these lenses, which allows you to isolate your subject from its background.
Uses: sports photography, wildlife photography

5) Big-Range Zoom Lens
Typical focal lengths: some range between 100-500mm (e.g. 35-350mm, 50-500mm)
Characteristics: These large and heavy lenses offer high quality images with subjects very far away. They are much more affordable than they used to be, but likely don't fit in an average camera bag, and are much heavier than your camera. They typically come with a tripod attachment, such that you can attach the lens to tripod instead of the camera body to achieve centre of balance.
Uses: wildlife photography


Manual Focus Zoom Lenses

6) Ultra-Telephoto Zoom Lens
Typical focal lengths: some range between 100-600mm (e.g. 400-600mm)
Characteristics: These large and heavy lenses offer high quality images with subjects even further away than big-range zoom lenses. They allow rapid manual focusing while tracking a subject.
Uses: wildlife photography


Author: Jennifer Clarkson is a Canadian photographer living in Ottawa. For more Photography Tips, or to view her Photo Gallery, please visit Jennifer Clarkson Photography.

Article source: Articlecat.com