Best Lens For Canon Camera

Helen asks…What is the difference betwen a Wide-angle lens converter and just a wide-angle lens?I have a Canon Rebel XT camera and i wanted to get a wide angle lens, i was just wondering what is the difference between the converter and the full wide-angle lens? Ive seen the wide-angle lenses but it seems like there so exspensive... Is there a difference in quality on a converter? And is it better to get a converter lens or the actual full lens? Maybe some good sites to buy these

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