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Miljenko Devcic | profile | all galleries >> tech >> Lens reviews and tests >> Kenko vs Sigma TCs tree view | thumbnails | slideshow

Kenko vs Sigma TCs

Frequent dilemma, particulary when using Sigma lenses is whether should we use Sigma or Kenko teleconverters. Another frequent question is how much pic quality deterioration can we expect when using TCs. Here I have tested both Kenko Pro 300 DG and both Sigma EX TCs. Chromatic abberation is multiplied by 10 in order to be seen well. The test bed was Nikon D70 and Sigma 150 mm f/2.8 EX Macro lens that displays pretty good characteristics (shown as well, without any TC).
4TCs.jpg
4TCs.jpg		 Sigma150_allTCs.jpg
Sigma150_allTCs.jpg		 Front side pic
Front side pic		 DG vs non-DG TCs
:: DG vs non-DG TCs ::

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Alex Z 24-Feb-2006 15:05
Thank you so much!!!
Miljenko Devcic24-Feb-2006 08:50
Hi Per, unfortunately, due to unknown reason, Sigma 150 Macro does not autofocus with any of the 2x TCs. I didn't mess with insulating contacts, but this method (known with Canon cameras) might trick the combo to start autofocusing.
Hi Alex, I have tried all presented TCs with some 20 or so lenses. The general conclusion is that Sigma lenses work perfectly with their own TCs. Opticaly and communicaton vise. Those combos report apertures correctly to the camera, which is not the case with Kenko combos. Yes, with some Sigma lens/Kenko TC you can get marginally better pic quality, but the combo might behave erraticaly when focusing and/or measuring. 100-300 is one of the rare Sigmas I didn't test, but according to other reviewers, it's a great piece of glass and works nicely with Sigma 1.4x TC. Regards, Miljenko
Alex Z 24-Feb-2006 04:11
Hi, I wonder if Kenko Pro 300 DG communicates correctly with Sigma 100-300 f4 HSM, i.e., focal length and f stops. Since Nikon metering system wants the right values to meter, if Kenko one could not pass the right information, then clearly Sigma TC is better?
Per S 31-Oct-2005 00:49
I appreciate the test! However, I am also interested in the AF performance. According to Sigma's own site, the AF will work with the 1.4x converter, but not with the 2x converter (seehttp://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3283&navigator=5). What is your experience about this? Is AF working with any of the 2x converters?

If not, can someone tell me why? With a 2x converter, the lens is f5.6 (I think) and fullfills the rule-of-thumb of teleconverters and AF I have heard of... The 2x converter also seem to work with Sigmas other f2.8 tele-lenses (seehttp://www.sigmaphoto.com/lenses/lenses_tele.asp).

Please, help me!
Per S 31-Oct-2005 00:31
I appreciate the test! However, I am also interested in the AF performance. According to Sigma's own site, the AF will work with the 1.4x converter, but not with the 2x converter (seehttp://www.sigmaphoto.com/lenses/lenses_all_details.asp?id=3283&navigator=5). What is your experience about this? Is AF working with any of the 2x converters?

If not, can someone tell me why? With a 2x converter, the lens is f5.6 (I think) and fullfills the rule-of-thumb of teleconverters and AF I have heard of... The 2x converter also seem to work with Sigmas other f2.8 tele-lenses (seehttp://www.sigmaphoto.com/lenses/lenses_tele.asp).

Please, help me!
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