Lens question/opinions

[Fotografer]

I am trying to get back into Wildlife/Landscape Photography after not having been very active with it for a while now.</p>
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<p>I've got a Canon EOS (film, not digital) that I am going to be using, atleast for a while yet. Although, I hope to move to digital as well sometime in the not to distant future.</p>
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<p>Anyways, I am looking for a new (on a budget - atleast for now) lens.</p>
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<p>I am thinking about either:</p>
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<p>Sigma Zoom Telephoto 70-300mm f/4-5.6 APO DG Macro Autofocus Lens for Canon EOS</p>
<p>or </p>
<p>Canon Zoom Telephoto EF 100-300mm f/4.5-5.6 USM Autofocus Lens </p>
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<p>And then maybe coupling it with a multiplier.</p>
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<p>Just wondering if anybody has used/does use either of these, and has any thoughts/recommendations/suggestions. I have read reviews on various sites, but would like some feedback from you guys as well.</p>
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<p>Thanks in advance for your feedback.</p>
<p>&n