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10-26-2010, 09:50 PM   #1
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IQ of Tamron 70-200 + TC better than DA 55-300?


I am wondering if pairing a teleconverter (say the Pentax one or the kenko one) with a Tamron 70-200 will result in equal or better IQ (at the same aperture) than the DA55-300?

The DA55-300 is fondly love by pentaxians as one of the sharpest zoom. I need the extra range but not keen to get the DA55-300 if the TC + Tamron strategy is a good one.

Anyone has the experience using a TC with the tammy? Interested to get some feedback.


10-26-2010, 10:29 PM   #2
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I have both lenses. The are really quite different lenses. The Tamron 70-200 is a f2.8 constant aperture lens that is big and heavy. It is very sharp and I'm getting very good results from it. I have the kenko 1.5x TC which speaks SDM, BTW. The Tammy works very well with it. No problems. The Tammy works as a close focusing lens too (from about 3 feet away). The downside is that it's slow focusing although the DA 55-300 is not any speed demon either. I haven't really compared the Tammy's sharpness with the TC in use but on the other hand when I do have it in use I can't tell it's there in the images. YMMV

The DA 55-300 is not constant aperture is lighter and has a longer reach. I've had good very results from it as well but it's just not as sharp IMHO. It's also much lighter.
10-26-2010, 11:10 PM   #3
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Thanks for the quick reply.

So putting in a TC will make the Tamron's AF much slower? hmm...not happy with this outcome.
10-26-2010, 11:19 PM   #4
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It's the case with *all* lenses. TCs will significantly slow down a lens's AF speed. Even still, the Tamron TC + 70-200 combo works very well. AF is fast enough as long as there's no end-to-end focus range hunting.

I have both lenses also and also vouch that the two lenses are of different leagues. There's *much* more to IQ than just sharpness, which would be hard to pick out between the 70-200+TC and the 55-300. DoF control and 3D effects are quite prominent with the Tamron, less so with the 55-300. But at the same FLs and apertures I've not seen dramatic difference in results between the two, except at f/5.6 (f/5.8 for the 55-300), which favours the 70-200.

10-27-2010, 03:45 AM   #5
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Thanks guys for the explanation. I think this is a no go for me.
10-27-2010, 10:20 AM   #6
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My TC (kenko 1.5) works with the 55-300 if the light is bright enough, which adds to its value. I seldom need such reach, but in a pinch it's there. Probably best to MF though; deninitely pokey autofocus.

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