D70s+sigma 50-500+which telecon for full AF (1 Viewer)

DeeJayTee · Dec 15, 2007

hello again, could someone give me information for a 1.4 telecon which would allow full AF on a D70s when coupled with a Sigma 50-500.
As my D70s manual says AF is only effective if an aperature of f5.6 or faster is used, with the 50-500 its max aperature is F4.6 at 50mm (a ok) at 500mm its F6.3 (would AF stillwork) and if a 1.4 telecon was used (if possible) with the lens at 500mm and being F6.3 + a 1.4 telecon which would make it a F8 (not to sure).
Thanks again David

rezMole · Dec 15, 2007

DeeJayTee said:
hello again, could someone give me information for a 1.4 telecon which would allow full AF on a D70s when coupled with a Sigma 50-500.
As my D70s manual says AF is only effective if an aperature of f5.6 or faster is used, with the 50-500 its max aperature is F4.6 at 50mm (a ok) at 500mm its F6.3 (would AF stillwork) and if a 1.4 telecon was used (if possible) with the lens at 500mm and being F6.3 + a 1.4 telecon which would make it a F8 (not to sure).
Thanks again David

I used a Kenko Pro 300 (?) 1.4X with my D70 and Tamron 200-500 which is also f6.3 at 500mm. AF still worked on bright days, but was very slow. Image quality suffered so much though that I never really bothered with the converter. Distant birds were brought closer but too much detail was lost.

Telecorder · Jan 12, 2008

Another alternative

would be the Sigma 1.4X TC with the first contact on the lens side taped over...
http://forums.dpreview.com/forums/read.asp?forum=1021&message=23560898&q=sigma+50+500+tc&qf=m

Both it and the Kenko Pro 1.4X TC will then allow AF w/good contrasting subjects. The previous poster's issue with TC AF on the 200-500 are more due to the screw drive AF. The Bigma's HSM isn't bad at all...

j palmer · Jan 15, 2008

hello david ive use dthe bigma on my 350d and 40d with a vivitar 1.4tc and af works only on the outer points ie. left and right on the 350d and 40d .
image IQ is still usable so long as you use the rule not to crop to much

hope this helps

D70s+sigma 50-500+which telecon for full AF (1 Viewer)

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