Tokina 2X TC problem with 70-200 L f/2.8

[Sajjad Yasin]

I recently got Canon 70-200L f/2.8. I also want to get a 2X TC for 70-200 so as a first try I got Tokina CA-F 2X teleplus MC4 on trail basis from shopkeeper (it is my first TC and I do not intend to keep it, i just took it for expermination , I have actually ordered Canon EF 2X TC).

The proble is that auto focus and metering works firne a 70mm but as I zoom in auto focus does not work & metering goes all weird (it just keeps changing shutter speed in aperture priority mode). Also I can use any aperture setting even below f/2.8which means that communicatin between lense & TC is not working.
If I use manual focus every thing works just fine and I have observe picture quality is not that bad with tokina (although due to manual focus & lower quality, the number of keeper pictures is small).

So if I change to EF 2X TC, will every thing work just fine ????? what if I go for EF 1.4X and not 2X ??? I know it is picture quality vs range..... so should I get 1.4X and then zoom/crop in photoshop CS2, will it be similar to EF 2X ??? with 1.4 X will I get any metering problem ???

[Sajjad Yasin]

waiting for your response please !!!!

[Jon]

The lens should be able to AF on that body even with a 2x TC on. That you're having trouble with both AF and exposure suggests that the TC may have a problem. Do you have (or have access to) any other lenses you can try it on?

[Sajjad Yasin]

Ok i will try it on my EF-S 18-55 & then report...

[Jon]

Ok i will try it on my EF-S 18-55 & then report...
I would not expect the 18-55 to AF with a TC, as Canon requires at least f/5.6 max. aperture for AF. The TC may not report the "adjusted" aperture to the camera, but the dimmer image will make AF more problematical, and encourage "hunting". You need to try with a fast lens (f/2.8 or faster) to get any assurance.

[Mitcon]

Does the Tonkina 4 element Tcon even connect to the EF-s Lenses ? But Jon is correct anyways so wouldn't be much point.

[Jon]

Does the Tonkina 4 element Tcon even connect to the EF-s Lenses ? But Jon is correct anyways so wouldn't be much point.
Good point - I'm not sure that any TCs come with support forthe EF-S mount.

[Sajjad Yasin]

OOPS, just could not connect EF-S 18-55 lense to TC. Any how I am returning the Tokina TC to shop keeper tomarrow & getting Canon EF 2X next week from him (he has ordered it for me). I have talked him on phone, he told me that L series lense have one extra pin in electric connection so my 70-200 f/2.8L will work with only EF TC's (he calls them "L" series TC because of their white colour !!!!!).

[Jon]

I have talked him on phone, he told me that L series lense have one extra pin in electric connection so my 70-200 f/2.8L will work with only EF TC's (he calls them "L" series TC because of their white colour !!!!!).
He's talking through his hat. The 70-200 will function with several other brands of TC. I suspect (absent the secondary test suggested) that the Tokina TC was defective. I use both Tamron and Canon TCs on my 100-400.

[Mitcon]

I have to agree again with Jon, but with third party Tcons I prefer the 7 element or pro versions to the 4 element units.

[Sajjad Yasin]

i do not have any other f/2.8 or lwer lense with me to check TC autofocus but when I go to shop to return the TC I will try to check it there.

[SYS]

I use Canon's 2x II TC to my 70-200L f/2.8 just fine. In fact, I posted some sample photos at 400mm focal length earlier today. It not only AF, but I'm happy with the speed of AF.

Your main concern really should be whether to get 1.4x or 2x rather than anything else. From my own experience, you DO get noticeable degradation in quality with 2x, so when I'm using 2x TC, I shoot extra images with the hope of having greater "luck." But then I'm not too thrilled with the idea of getting the 1.4x just to get 80mm additional FL. I think I'll get 1.4x when I get my 100-400L or perhaps even 500L prime....