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12-20-2010, 07:24 PM   #1
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What teleconvertors work with what telezooms?


Can anyone summerise what 1.4x teleconvertors work with what 70-200/2.8 telezooms (Sigma(s), Tamron, ??) and effect on AF and image quality?

If you own one of these combo's are you happy to strap the TC on or is it a last resort to obtain the extra reach?

Wondering if this is a viable alternative to a Sigma 100-300/4 (can't buy one new... need to see in person before buying 2nd hand) or Pentax 60-250/4 (don't trust the SDM at the moment and would prefer a little longer than 250mm)

In theory it sounds good... the benefits of wideish aperture on the 70-200/2.8 then strap on the TC for a 98-280/4

Another possibility is the Sigma 120-400/4.5-5.6 but that's getting a bit slow aperture-wise for my liking

Feel free to add your experience or thoughts...

Regards, Nige

12-21-2010, 05:57 AM   #2
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I can't give the whole list but I can start it

Sigma TC work only with sigma screw drive lenses not the newer SSM lenses and are excellent BUT they have an optical design that protrudes into the lens therefore your lens needs a 35 mm diameter by 12 mm deep recess to accept the TC. These TCs are only meant for a few really fast sigma and pentax lenses

Pentax makes a very capable 1.7x autofocusing TC that converts any lens into a semi AF lens
12-21-2010, 04:40 PM   #3
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Original Poster
thanks for that info... it's all a bit confusing!

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