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|| SportsShooter.com: Member Message Board
Xtenders and autofocus
Les Schofer, Assistant
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Lynchburg | VA | USA | Posted: 11:58 AM on 10.13.09 |
->> I suspect but am not sure that using a 2x or 1.4 Xtender (Canon here) slows the response of the Autofocus. Does anyone know if this is definitively so?
Les Schofer |
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Louis Lopez, Photographer
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Fontana | CA | USA | Posted: 12:27 PM on 10.13.09 |
| ->> yes. |
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Jeff Mills, Photographer, Photo Editor
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Columbus | OH | USA | Posted: 12:42 PM on 10.13.09 |
->> Yes it does, not only due to the effect of less light hitting the AF sensors, but I also believe that Canon's own 1.4 and 2x TC's actually tell the camera to slow its AF a bit to allow for better accuracy.
I can't remember exactly where I read that but believe it was in some white paper or PDF guide.
I don't shoot Canon anymore but remember a few guys that preferred Kenko or Sigma TC's because they didn't do this. Still had the obvious effect of having less maximum aperture though.
I used to use a 1.4x on my 400 2.8 quite a bit and never really found it to take much of a toll either on the IQ or AF speed.
2x was a different story as that did slow things down and you would see some image degradation. Canon's 2x worked much better than Nikon's 2x though which is just plain bad.
The 1.4x even worked well on the 70-200 but the 2x really was lacking on the zoom. |
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Eric Canha, Photographer
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Brockton | MA | United States | Posted: 1:25 PM on 10.13.09 |
->> I don't know about Canon or 2x BUT on a Nikon 300 2.8 VR the Nikon TC 1.7x works WONDERFULLY. I'm hard pressed to notice any slowness in AF and as a 500 f4.8 the setup is razor sharp wide open.
The 300 /w TC has become my standard daytime football and soccer setup. Even wide open the fabric weave is seen. I think that one of the things to keep in mind is whether you are using newer afs / usm technologies. I know that the 300 AF-s didn't fare as well as what I'm getting with the new 300. |
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Randy Abrams, Photographer
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Bath | NY | US | Posted: 12:06 PM on 10.15.09 |
| ->> One thing you might find also is that TC's can be a little fickle. I've heard several people say that after getting a third copy they finally found one that worked well with their lens. In my case I use both the Nikon 1.4 and 1.7 tcs with my 300 and 400/2.8s. Ironically my 1.7tc is sharper on my 400 than my 1.4. |
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Darren Whitley, Photographer
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Maryville | MO | USA | Posted: 12:42 PM on 10.15.09 |
| ->> I have shot with the 1.7 and a 70-200 VR at a high school soccer this fall and I'm simply impressed. That is one "crispy" extender. |
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Chuck Steenburgh, Photographer
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Lexington | VA | USA | Posted: 3:10 PM on 10.15.09 |
->> I use a Kenko 1.4x (supports AF-S or USM in Canonspeak) on my Sigma 120-300 (HSM in Sigmaspeak or USM in Canonspeak). It does hunt a bit but works well. (My Sigma 1.4x bit the dust, it didn't hunt as much tho.)
The Kenko has the advantage of working both with lenses with on-board motors, and on lenses without. It works great with my 180/f2.8 old-school AF lens. It is famously incompatible with my Nikon 80-200/f2.8 AF-S lens, tho, for which I acquired a genuine Nikon TC.
One of these days I'll be able to afford Nikon long glass and the 1.7x Nikon, which by all accounts is a dream. The Nikon 2x is indeed a dog, at least on my 80-200. |
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Gene Boyars, Photographer
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Matawan | NJ | United States | Posted: 12:09 PM on 10.16.09 |
| ->> As Jeff said, the loss of light will make your Canon AF work slower. It is always a good idea to send or take your lenses and the TC to Canon and let them do a one time custom match. That helped me a lot. |
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