For photographers using Canon gear, a Canon wide angle lens is an essential tool. This is because the wide angle is widely regarded the most indispensable of all lenses.
In situations where a telephoto lens would be handy but you don't own one, you can usually move closer to the subject or crop the image in your image editing software to fill the frame with your subject.
Unfortunately there is no comparable workaround if you don't have a wide angle lens. Should you want your landscape to include foreground detail plus distant mountains, you'll have to move back a very long way to fit in the whole scene with a standard 50mm lens.
Similarly, when photographing interiors, space is often tight, leaving you no room to move further away to include more of the scene, making it essential to use a wide angle lens.
If you use a Canon digital SLR camera such as one of the Canon Digital Rebels (Canon EOS 400D, 450D, 500D) or a Canon 40D or 50D, then it's important to understand that these cameras are fitted with APS-C sensors that are smaller than a full-frame sensor.
This has the effect of magnifying the image when using normal Canon EF lenses designed for use with full-frame digital or 35mm SLR cameras and has the same effect as fitting 1.6x converter to the lens.
While this is a bonus for photographers using telephoto lenses, it works against wide angle lenses, effectively making them longer -- so your 24mm wide angle on a Digital Rebel becomes a 38mm (24 x 1.6), i.e. close to a standard lens rather than a wide angle. To find out more about the impact of sensor size on a lens's focal length, see Canon Digital SLR Crop Factor.
In situations where a telephoto lens would be handy but you don't own one, you can usually move closer to the subject or crop the image in your image editing software to fill the frame with your subject.
Unfortunately there is no comparable workaround if you don't have a wide angle lens. Should you want your landscape to include foreground detail plus distant mountains, you'll have to move back a very long way to fit in the whole scene with a standard 50mm lens.
Similarly, when photographing interiors, space is often tight, leaving you no room to move further away to include more of the scene, making it essential to use a wide angle lens.
If you use a Canon digital SLR camera such as one of the Canon Digital Rebels (Canon EOS 400D, 450D, 500D) or a Canon 40D or 50D, then it's important to understand that these cameras are fitted with APS-C sensors that are smaller than a full-frame sensor.
This has the effect of magnifying the image when using normal Canon EF lenses designed for use with full-frame digital or 35mm SLR cameras and has the same effect as fitting 1.6x converter to the lens.
While this is a bonus for photographers using telephoto lenses, it works against wide angle lenses, effectively making them longer -- so your 24mm wide angle on a Digital Rebel becomes a 38mm (24 x 1.6), i.e. close to a standard lens rather than a wide angle. To find out more about the impact of sensor size on a lens's focal length, see Canon Digital SLR Crop Factor.