Sigma 50-500 - got AF when using TC?

EchiDna · 2nd March 2004

Hi guys, just wondering if anyone try the Sigma 50-500 with a TC and if so, does it retain AF or not? Canon mount if that makes a difference!

TIA,

lOrBeRt · 2nd March 2004

Not possible. As the aperture size is btw 4-5.6 if I am not wrong. With TC, it becomes f8-f11 and anything beyond f8 will cause the AF to hunt like mad. I have tried both Canon and Kenko ones, have yet to try Sigma's own, perhaps it might work?

rncw · 2nd March 2004

be it canon or nikon, i think they should be about the same...

Originally Posted by From Sigma's Web Site

Focusing
On the lists, the lenses marked "AF" will retain auto focus operation when used with a Tele Converter. The lenses marked "MF can only be used for manual focus.
On the list of Canon AF, some lenses are working AF, even the though list says MF.
Some lenses will be operated AF even the list of MINOLTA AF, NIKON AF, PENTAX AF mentioned "MF", however, be aware that these lenses cannot focus precisely by auto focusing. Also, it is possible to make some trouble. Therefore, please be sure to use with MF.
*1 With 1.4x APO Tele Converter, AF can operate at distances more than 1.2m from the subject. If the subject is closer than 1.2m, only MF is available.
*2 When the Tele Converter is attached, the zoom range will be restricted to between 100mm to 500mm.

http://www.sigma-photo.com/html/page...ComptChart.htm

i haven't tried it yet...

EchiDna · 2nd March 2004

thanks for the quick replies!

hmm... maybe I'll have to make do with 50-500 then ;-)

ST1100 · 3rd March 2004

The 50-500 is f6.3 at the long end. Most Canon bodies cannot AF at that aperture even without the TC. Only the 1-series and the EOS 3 can AF up to f8; the rest stop at f5.6.

2nd March 2004	#1
EchiDna New Member Join Date: Feb 2004 Posts: 22	Sigma 50-500 - got AF when using TC? Hi guys, just wondering if anyone try the Sigma 50-500 with a TC and if so, does it retain AF or not? Canon mount if that makes a difference! TIA,

2nd March 2004	#2
lOrBeRt Member Join Date: Dec 2003 Location: fiat.sg Posts: 191	Not possible. As the aperture size is btw 4-5.6 if I am not wrong. With TC, it becomes f8-f11 and anything beyond f8 will cause the AF to hunt like mad. I have tried both Canon and Kenko ones, have yet to try Sigma's own, perhaps it might work? __________________ Lorbert.Tay@Fiat.SG

3rd March 2004	#5
ST1100 Senior Member Join Date: Jun 2003 Location: Singapore, Bedok Posts: 1,801	The 50-500 is f6.3 at the long end. Most Canon bodies cannot AF at that aperture even without the TC. Only the 1-series and the EOS 3 can AF up to f8; the rest stop at f5.6.