What is th edifference between these 2 lens Canon EF-S 55-250mm f/4-5.6 IS and Canon EF-S 55-250mm f/4-5.6 IS II??
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The specifications are identical:
While I haven't used or seen reviews of the new II version, the new version is unlikely to have significant changes to the optic quality. There's a discussion here on this topic. Possible changes involve a minor adjustment to the IS algorithm to allow different behaviour when panning and/or minor lens coating changes.