0ur opinion:

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The EF17-40mm f/4L USM is an ultra wide angle Canon EF zoom lens meant for professional and high amateur SLR E0S camera users.While it is an excellent lens when used with an analog SLR camera, the EF17-40mm f/4L USM is especially well suited for digital SLR cameras with an imaging sensor size smaller than the 35mm format. lndeed on such digital SLR cameras these focal lengths can give an angle of view approximately equivalent to that of a 28-70mm lens used on a 35mm camera, which makes it the ideal standard zoom lens.The EF17-40mm f/4L USM has 12 lens elements arranged in 9 groups. Super Spectra Coating on the elements ensures excellent color balance and minimizes ghosting and flare. To provide superb image quality over a 17-40mm zoom range the lens uses three aspheric elements of two different types, while Super UD (Ultra-low Dispersion) glass is used to prevent the chromatic aberrations that often can degrade the subject edge clarity.Minimum focusing distance is just 28mm throughout the entire zoom range. The Auto-focus works silently and quickly thanks to a fast central processing unit with an improved AF algorithm. You can override AF mode with manual focus should you wish. Controlled by an electromagnetic diaphragm, the EF17-40mm f/4L USM's circular aperture can achieve a more attractive appearance to out of focus background areas in a picture. The front of the lens does not rotate as you focus. This means, for example, that polarizing filters still function effectively as you zoom in and out. At the rear of the lens there's a drop-in gelatin filter holder. Highly resistant to moisture and dust, the EF17-40mm f/4L USM is ideally suited for use in harsh environments. Environment friendly lead-free glass is used throughout its construction.

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Broaden your perspective with the Canon EF 17-40mm ultra-wide-angle zoom lens. ldeal for both film and digital SLR cameras, the lens offers three aspherical lens elements in addition to a Super UD (ultra-low dispersion) glass element, creating superior optics in all conditions. ln addition, the lens focuses as close as 11 inches (0.28mm), and offers both Canon's full-time manual focus and a powerful ring-type ultra-sonic monitor (USM) that produces fast and silent autofocus. 0ther features include a constant f/4 maximum aperture, the choice of screw-in 77mm filters or a holder in the rear of the lens for up to three gel filters, and optical coatings optimized for use with digital cameras. Boasting weather-resistant construction similar to other high-end L-series cameras, the lens carries a one-year warranty.

• Focal length: 17-40mm
• Maximum aperture: 1:4
• Lens construction: 12 elements in 9 groups
• Diagonal angle of view: 104 to 57 degrees (at 30 feet)
• Focus adjustment: lnner focusing system with USM
• Closest focusing distance: 0.9 feet
• Zoom system: Rotating type
• Filter size: 77mm
• Dimensions: 3.3 inches in diameter, 3.8 inches long
• Weight: 1.1 pounds

Some more accessories for this product for you:
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Some more accessories for this product for you:

• Tiffen 77mm Wide Angle Filter Kit
• Tiffen 77HTCP 77MM Digital HT Circular Polarizer Titanium Filter
• Tiffen 77HTCGND6 77MM Digital HT Grad ND 0.6 Titanium Filter
• Tiffen 77HTHZE86 77MM Digital HT HAZE 86 Titanium Filter
• Tiffen 77HTSTR42 77MM Digital HT Star 4 PT 2 Titanium Filter

Piece Availability: Usually ships in 24 hours

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Buyer's feedback: - * An excellent lens ...
This lens seems sharp at all distances and apertures. We are very pleased with it.

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Buyer's feedback: - Now, THIS is a lens!
No plastic grinding against plastic when you focus this thing. Feels just like my Fujinon lens I use on my TV news camera. Pro gear. Want some? Pay up.

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Buyer's feedback: - * Great Lens ...
I bought this with my Canon 30D. This is a great lens and L series is the best. I have mostly L lens because the quality is worth the money.

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Buyer's feedback: - Great on full frame, average on crop bodies
This is a good lens, but it's certainly not great. Along with all other L-series lenses, it's more durable, weather resistant, doesn't rotate the front element. It has a virtually silent focusing motor which is a pleasure to use. The lens is light, feels solid.

But as far as quality is concerned, it's average. On a full-frame camera, such as the 1Ds or the 5D, the corners are much sharper than that of a 28-135, for example. But on a cropped-sensor camera such as the 40D or the XTi, you will not see almost any difference in quality between this and the 18-55mm kit lens. I've tried, you just can't. If you're trying to stay on a budget, look into the cheaper EF-S, Sigma or Tokina alternatives.

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Buyer's feedback: - * newest most used glass! ...
this lightweight little wonder is always on my camera, i really hardly ever take it off...i do however, find the hood a bit...much, that being said the feel and operation is obviously that of an 'L' lense