| The digital SLR crop factor, or lens multiplication | | | | 18-55mm. This would be classified as "ultra wide" |
| factor, has the effect of cropping the edges of | | | | (at the wide end) for a 35mm camera, but |
| an image and enlarging the central area. The end | | | | equates to a more mundane 28.8-88mm -- or |
| result is similar to using a longer lens, or a tele | | | | standard zoom -- when used with a Rebel XSi or |
| converter. | | | | 50D. |
| The cropping effect occurs because the sensor | | | | While Canon's Rebels and EOS **D digital SLRs |
| on most digital SLR cameras is smaller than a | | | | are categorized as entry-level or "prosumer" |
| 35mm slide or negative. A "frame" of 35mm film | | | | cameras, they are also used by professionals, |
| is 36 x 24mm in size, while the digital sensor on | | | | particularly wedding photographers, who previously |
| Canon Digital Rebels (300D to 500D) and the EOS | | | | were not being adequately catered for by the |
| **D range (20D to 50D, and 7D) is only 22.5 x | | | | wide angle lenses available, particularly in terms of |
| 15mm in size. A smaller sensor to receive the | | | | image quality and focal length. |
| image means that some of the image will be | | | | To overcome this, Canon introduced two lenses |
| cropped. | | | | that are standouts within its range of EF-S lenses |
| Think of it this way: you're watching a slideshow | | | | for use on Rebel and EOS **D cameras: |
| on a screen that's just big enough to | | | | * Canon EF-S 17-55mm f/2.8 IS USM |
| accommodate the full-size image, then someone | | | | * Canon EF-S 10-22mm f/3.5-5.6 USM |
| substitutes the screen with one that's smaller. | | | | The EF-S 17-55mm is notable for its constant f |
| Now some of the projected image (the top, | | | | 2.8 aperture throughout the zoom range which, |
| bottom, and sides) "overflows" the smaller screen, | | | | together with image stabilization, makes it |
| so what you now see is a cropped version of the | | | | especially effective for shooting in low light |
| image. | | | | without flash. It is highly rated by wedding |
| You get a similar result when using a digital SLR | | | | photographers, and also as a portrait and |
| camera with a sensor that's smaller than a piece | | | | walkaround lens. |
| of 35mm film -- the image cast by the lens | | | | Users like the lens for its sharp images at all focal |
| "overflows" the sensor. Any spare space around | | | | lengths, fast autofocus, versatility and excellence |
| your subject is cropped away, so the subject | | | | in low light. Their main dislikes are the price (it's |
| now fills more of the frame -- but if there's no | | | | the most expensive EF-S lens), inadequate |
| spare space, part of the subject itself gets | | | | weather sealing, plus the size and weight. |
| cropped. | | | | It nevertheless receives a rating of 91% from |
| This cropping or magnification effect is an | | | | users and is highly recommended as a superior |
| advantage when using a telephoto lens, as the | | | | quality lens for APS-C format cameras. |
| result is similar to using a longer lens or 1.6x | | | | The EF-S 10-22mm is remarkable as it's the only |
| converter. | | | | true ultra wide angle for Canon Rebels and EOS |
| However, for anyone shooting wide angle, the | | | | **D bodies. Fit this lens on your Canon 40D and |
| opposite is true. Now that awesome wide angle | | | | it's equivalent to a 16-35mm on a 35mm or |
| so prized for creating dramatic landscapes or | | | | full-frame body, offering photographers creative |
| shooting tight interiors is rendered semi useless. A | | | | opportunities not otherwise possible with APS-C |
| genuine wide angle lens like a Canon EF 24mm | | | | format cameras. |
| gets "lengthened" by 1.6x, giving it an equivalent | | | | Users like the lens for its sharpness, excellent |
| focal length of 38.4mm on your Rebel XSi or 50D. | | | | colors, fast autofocus and minimal distortion. They |
| Fortunately, Canon and other manufacturers of | | | | dislike the price, plastic construction, and lack of a |
| digital SLR's realized they had to produce lenses | | | | provided lens hood. |
| to overcome the crop factor for photographers | | | | But image quality is favorably compared to that |
| using wide angle lenses. | | | | of a Canon L-series lens, and users give it a rating |
| The result is a range of lenses created specifically | | | | of 90%, recommending it as essential for anyone |
| for digital SLR cameras with sensors smaller than | | | | wanting genuine wide angle capability on a Rebel |
| 35mm film (often referred to as APS-C format | | | | or EOS **D body. |
| sensors). While the crop factor still applies when | | | | Users of Canon Rebels or EOS **D SLRs can no |
| using these lenses, the lenses themselves are | | | | longer blame their kit lenses for less than stellar |
| "shorter", both physically and in focal length, than | | | | image quaility -- alternatives are available (albeit at |
| the equivalent lens for a 35mm camera. | | | | a price. |
| Thus the kit lens for Canon Rebels is the EF-S | | | | |