tamron 18-250 not really 250 at long end

Started Feb 4, 2008 | Discussions thread
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dwalby
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tamron 18-250 not really 250 at long end
Feb 4, 2008

I've had this lens for a few weeks now and after using it at the long end a few times it didn't seem as long as I was expecting for 250mm focal length.

So I did a quick FOV test with it and sure enough, according to my calculations the FOV would indicate its closer to 180mm at the long end, not 250mm.

The actual focal length seems to be true to the barrel markings up to 100mm or so, then it gets optimistic after that. I wouldn't be surprised by something like 5-10% variation or so, but this is ridiculous, its off by 25-30% at the long end.

Anyone else notice this?

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