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Old Feb 7, 2009, 1:34 PM   #1
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From this morning. The first is with the 18-55 DA kit lens and the other 2 are with the Sigma 50-500 with a Sigma 1.4 TC. I set the Kit lens at 35mm so you would have a "normal" look at the shot first. Some folks think the Sigma 50-500 can't zoom down lower than 100mm when the Sigma APO teleconverter is attached...not so...with care you can go to 58mm with the combo I have. Also it focuses quite well at very high f/stops.
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Old Feb 7, 2009, 1:34 PM   #2
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Old Feb 7, 2009, 1:35 PM   #3
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Old Feb 8, 2009, 7:35 AM   #4
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To be honest I would be more interested in seeing the wide open / stepped down once performance, as I rarely shoot that way you did... but still it's a nice experiment. Seems the Sigma TC works well with the Bigma. (I would have been disappointed if that wasn't the case)

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Old Feb 8, 2009, 9:10 AM   #5
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The reason for this is someone said you couldn't focus at f/stops above f/8 or so when using the Bigma or most any other lens while using a TC.

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Old Feb 8, 2009, 12:15 PM   #6
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bigdawg wrote:
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The reason for this is someone said you couldn't focus at f/stops above f/8 or so when using the Bigma or most any other lens while using a TC.
Since your Sigma 1.4X APO TC doesn't report the corrected focal length and aperture to the camera, any lens that will autofocus without it will autofocus with it.

But if a teleconverter reports the corrected focal length and aperture to the camera (i.e.: any 2X and some 1.4X teleconverters), and the corrected maximum aperture is smaller than f/8.0 (at certain focal lengths) the camera won't even try to autofocus (at those focal lengths.)
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