If you're buying a DSLR, it won't take long for you to realize the glass you attach to it is going to be very important. Unless you want to look like a total dweeb (me for instance) carrying around a backpack full of gear, you'll need what photographers refer to as a "walk-around" lens. That's one lens performing a multitude of jobs. Unfortunately, there's a plethora of them, making your decision that much more difficult.

You might buy a lens from your camera's manufacturer, like Canon or Nikon, or get something a little less pricey from a third-party brand. That's where Tamron comes in with its announcement of an 18-270mm lens for Canon and Nikon mounts. Though it's available only in Japan to begin with, this lens is expected to make its way to the states shortly. As far as I know, it's the first 15:1 zoom available for DSLR cameras, and Tamron claims it's the widest-range DSLR zoom lens made.

If you're thinking 18-270mm scratches a whole lot of itches, you're right! 18mm, even with a "crop factor," is a pretty wide-angle lens. 270mm, especially with a "crop factor," is a very long lens.

"With its vast zoom-range, the Tamron AF18-270mm F/3.5-6.3 Di II VC lens enables the user to cover virtually any photographic subject from wide angle to ultra telephoto simply by turning the zoom control. It covers angles of view equivalent to 28mm to 419mm when converted to the 35mm format. In addition, this breakthrough lens is equipped with Tamron's exclusive, proprietary tri-axial Vibration Compensation (VC) mechanism that eliminates or substantially reduces the effects of handheld camera shake. As a result, the user can enjoy the convenience of handheld photography in virtually any situation, from shooting candid images, to covering sporting events, to news photography, without worrying about camera shake having an adverse effect on image quality. The new lens will be made available in Canon and Nikon mounts"

Make no mistake: There are compromises when a lens tries to be all things at once. Prime lenses, those with a single focal length, are less complex and nearly always sharper. They're also faster, allowing more light to reach your camera's sensor, which in turn lets you shoot in lower light. At f/3.5 to f/6.3, this probably isn't going to be the right lens for indoor, low-light situations. Tamron has announced a "proprietary tri-axial Vibration Compensation (VC) mechanism that eliminates or substantially reduces the effects of handheld camera shake," but it's not revealing how many f-stops that compensation buys you.

In recent years Tamron has been a good value for the price, undercutting more sophisticated and expensive lenses from the camera manufacturers themselves. If the company can do that again in a lens with this kind of versatility, a lot more people will be walking around with Tamron glass.