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10-06-2014, 12:19 PM   #1
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AF Working!! K-3 +Sigma Ex 180mm f3.5 Macro + 1.4x, 2.0x Tc

( I don't know if this has been confirmed by others)

I was testing the Sigma 1.4x and 2.0x TC on my Sigma Ex 180mm f3.5 Macro, and to my surprise the AF was working in combo on my K-3. This surprised me because Sigma on its website lists both TC as working in MF mode only. I don't know the service history of my 180mm, whether it was re-chipped or not but the AF performance is pretty good. Out of the 10 reviews on this lens, only one mentions stacking TC with it and none on its AF functionality. IQ performance is yet to be determined. The serial on the 180mm is No.1003838. (I have an Sigma APO 400mm f5.6 Macro coming in a week or so, I'll test both converters when i get a chance)

I wonder how many other lenses not listed on the compatibility website might have their AF feature enabled as well.

Note: On Sigma's website the @70-200mm f2.8 HSM AF feature is listed as working with both the dedicated 1.4x and 2.0x, but I've personally found this not to be the case (both K5 and K3 camera menus flash in error) In addition, attaching both converters on top of each other on the Sigma 180mm f3.5 doesn't produce any results (It engages the lenses motor but it doesn't achieve focus) It is also painfully slow unlike the Sigma Ex 300mm f2.8 which both nails focus faster and accurately (even when both TC are combined together)

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Last edited by Stavri; 10-06-2014 at 06:23 PM.
10-06-2014, 02:45 PM   #2
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That's awesome!
10-06-2014, 05:58 PM   #3
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If I am not mistaken one of the problems with the Sigma TCs is that the rear element of the lens can end up touching the glass in the TC. I am not 100% sure and I have no idea whether it applies to the 180 or not but that is what I recall.
10-06-2014, 06:25 PM   #4
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QuoteOriginally posted by sergysergy Quote
If I am not mistaken one of the problems with the Sigma TCs is that the rear element of the lens can end up touching the glass in the TC. I am not 100% sure and I have no idea whether it applies to the 180 or not but that is what I recall.
The 180mm f3.5 doesn't have that issue. I also have confirmed from another forum member that the 1.4x works with the Sigma APO AF 400mm f5.6 Macro (although its slow to nail focus)

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