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Author Topic: Tamron SP AF 1.4X and Canon 40D  (Read 5927 times)  bookmark this topic!
canoeracer
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Tamron SP AF 1.4X and Canon 40D
« on: November 09, 2008, 12:55:19 PM »

I recently purchased a new Tamron SP AF 1.4X teleconverter.  When used with my 40D, it does not recognize a Canon EF 100mm f/2 lens.  It does, however, meter correctly on my Canon EF 70-200mm f/4L.   Is this normal?   Tamron claims it works with lenses >90mm and f/4 or faster.

Thanks
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Bob Atkins
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Re: Tamron SP AF 1.4X and Canon 40D
« Reply #1 on: November 09, 2008, 03:27:48 PM »

I'm not quite sure what you mean by "recognize" in this context.

The Tamron 1.4x should work with any lens, i.e. it should give you the correct exposure (even though the indicated aperture may be off by a stop).

I've used a Tamron 1.4x with lenses from 50mm to 600mm and it's "worked" with all of them. Sometimes I've used a little exposure compensation with some camera bodies to get the exposure I liked best, but by and large exposure has been pretty accurate and normally no compensation is needed. I haven't used it with the 100/2 because I don't have one, but I can see no reason at all why there should be a problem.
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canoeracer
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Re: Tamron SP AF 1.4X and Canon 40D
« Reply #2 on: November 10, 2008, 05:54:28 AM »

By recognize I mean the camera body still sets the lowest aperture to 2.0 on the Canon 100mm, rather than the anticipated 2.8.   When I use the 70-200 f/4, the aperture shifts to f/5.6.   The pictures I take even with the 100mm at any available aperture are under exposed using the 1.4x.   Also, as I understand other reports, the Exif data should indicate that a converter is being used.   This does not happen.

Any further thoughts?    Do you think the converter is defective?

Thanks
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