04-04-2014, 12:03 PM
We need to break it down to two parts: mechanical compatibility, and electrical compatibility. Without seeing and trying it ourselves, we can only go by the comments provided.
If there is suspected mechanical interference you might try putting manually moving the focus and seeing if you can get the whole range, or if it becomes blocked at any point.
With Sigma's own 2x+macro combination, I suspect they disable AF as the effective aperture at closer distances is then far exceeding f/5.6, therefore phase AF would either not work or be unreliable. I think they could have allowed AF at longer distances if they wanted to though.
http://www.sigmaphoto.com/teleconverter-compatibility
If there is suspected mechanical interference you might try putting manually moving the focus and seeing if you can get the whole range, or if it becomes blocked at any point.
With Sigma's own 2x+macro combination, I suspect they disable AF as the effective aperture at closer distances is then far exceeding f/5.6, therefore phase AF would either not work or be unreliable. I think they could have allowed AF at longer distances if they wanted to though.
http://www.sigmaphoto.com/teleconverter-compatibility
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