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Old Jan 14, 2008, 9:18 AM   #1
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I recently picked up a used Tamron 18-250mm lens based on the excellent reviews and experiences of others who have used it and much to my disappointment I find that it doesn't zoom anywhere near 250mm - it looks to be about 190-200mm at most. I compared it to my beloved 70-210mm Minolta "beercan" and the 250mm setting on the Tamron covers significantly less area than the 210mm setting on the Minoltal lens? What gives here? Has Tamron exaggerated beyond reason the zoom range on the lens or is my "beercan" lens really a 70-260mm? For what it is worth, the 18mm setting on the Tamron compares very well to other lenses at 18mm. Has anyone seen a proper lens test on the Tamron that shows the real zoom ratio and focal lengths on this lens?
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Old Jan 14, 2008, 9:37 AM   #2
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It's the focus distance.

Effective focal length with a number of lens designs will change with focus distance.

The focal length range in the specs assumes infinity focus. If you want something closer to what a different lens set to 250mm would give you, you'll need to focus on something closer to infinity (further away).

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Old Jan 14, 2008, 9:37 AM   #3
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I just found a discussion on this listed under Tamron 18-250mm zoom problem. It appears that my problem is not a problem at all when the lens is focused at infinity. It is only when it is focused at less than infinity that the angle of view varies. Sorry for bringing up an old topic but it didn't show in the initial search. Cheers!
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Old Jan 22, 2008, 11:07 PM   #4
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Ordview wrote:
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I just found a discussion on this listed under Tamron 18-250mm zoom problem. It appears that my problem is not a problem at all when the lens is focused at infinity. It is only when it is focused at less than infinity that the angle of view varies. Sorry for bringing up an old topic but it didn't show in the initial search. Cheers!
Don't feel bad... I think most of us have fallen for that old "this lens" doesn't zoom anywhere near XXXmm trick. LOL
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