Kenko 2x teleconverter, have I got it wrong?

footman

footman

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Laurence
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I'm getting a 1D MkIV later this week so I bought a Kenko 2x TC to have a play with my 300mm F4.
The TC arrived today so I stuck it on a 5DII with the 300 f4 to see how MF would work. I was somewhat taken aback when it AF'd perfectly and I took some shots.
To confirm this I changed the body for a 7D, it still worked! I changed the lens to a 70-200 F4 and it AF'd with that. It failed on a 400 f5.6.

I've always been under the impression that a 1.4X TC works on a non-1D body with an f4 lens (which I do use) but to use a 2X TC I'd need a 1D body.

The next oddity comes when I try to import the file. My LR3 is screwed anyway, crashes after 5 seconds but I can briefly see the file on the import screen.
Elements will import but says the file is corrupted. Both DPP and my computer tell me the card reader is empty.

However, Irfanview will see the file and open it. On the exif it plainly shows the shot was taken at 600mm.

The only partial explanation I have is that I use back-button focussing, I don't know if that can have any bearing.
 
Most 2x converter work best with fast lens F2.8,as you have found out its alway luck of the draw,when useing them with slower lens :)

Your best bet would be to get the Canon one.
 
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footman said:
I've always been under the impression that a 1.4X TC works on a non-1D body with an f4 lens (which I do use) but to use a 2X TC I'd need a 1D body
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Its the canon TCs that work that way, so autofocus upto f5.6 on entry / semi bodies and f8 center focus point on 1D series bodies. The 3rd party TCs seem to work (ie autofocus) but I think its down to how the canon v 3rd party TC communicate with the camera. The problem with the 3rd party TCs (similar to the sigma 50-500mm f6.3 lens, which cheats the camera into thinking its f5.6 so it will autofocus) lies in the fact that it may damage the focus motor on the lens because the lens will hunt beyond the limits and cause issues with the lens over time.
 
pete.rush said:
Its the canon TCs that work that way, so autofocus upto f5.6 on entry / semi bodies and f8 center focus point on 1D series bodies. The 3rd party TCs seem to work (ie autofocus) but I think its down to how the canon v 3rd party TC communicate with the camera. The problem with the 3rd party TCs (similar to the sigma 50-500mm f6.3 lens, which cheats the camera into thinking its f5.6 so it will autofocus) lies in the fact that it may damage the focus motor on the lens because the lens will hunt beyond the limits and cause issues with the lens over time.
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The sound of this damaging the lens quite scares me. Untill recently i thought a tc on a sigma 150-500 wouldnt work (certainly the autofocus with a kenko 2x didnt). I read a post somewhere on here that they were using a 1.4tc with there sigma 150-500 - im scratching my chin at the moment wondering whether i should get one.

I'll be watching this thread with interest :geek:

Coley
 
The new Kenko Pro300 DGX will AF on most lenses up to f8 on most of the better bodies. I had my 1.4x working perfectly with a Canon 100-400 L on both a 7D and a 5D2 and in good light (not direct sun, but bright) it didn't have to hunt for the focus. It was fast and accurate and while it's like this you wont damage or wear out the AF motor. Only in poor light does it become a problem at all, but then it depends how much you use it/need it.
I've had a Sigma 150-500 OS on the TC as well and it reads as a f9 at the 500 end and definitely wont AF with it. But if you turn the AF off on the lens you can use it with manual focus and have no problem. I used it to get some pics of a full moon and the IQ was very good even with the TC on.
 
Hi footman this has nothing to do with your queary but i notice you live in Hampton.
Myself,wife and 2 children have a wedding at Hampton court palace golf club later on in the year and wondered if you could recommend accomodation in the area that doesn't cost an arm and a leg and is also near transport into London.

thanks
 
steunited said:
Hi footman this has nothing to do with your queary but i notice you live in Hampton.
Myself,wife and 2 children have a wedding at Hampton court palace golf club later on in the year and wondered if you could recommend accomodation in the area that doesn't cost an arm and a leg and is also near transport into London.

thanks
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Can't say that I know of any but have a look here:
http://www.expedia.co.uk/Hampton-Court-Hotels.d182536.Travel-Guide-Hotels
I would say that the Charlton on The Green hasn't got a good rep round here.

also try Premier Inns, there are quite a few round here.
 
footman said:
Thanks for the replies. The AF time on these bodies seems as quick as without the 2x TC and the exif data shows that it was shot at f8.
Does that mean the camera is not being fooled?
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This is my understanding of how things work:
Reporting TCs (Canon I & II, Kenko DG, Sigma): A TC-compatible lens (e.g. 400/5.6) detects the presence of a TC through the 3 extra contacts and reports the correct f-stop for the combination to the camera. If the f-stop is above f/5.6, AF is disabled for non-1-series bodies.

Non-reporting TCs, or taped TCs, or TCs with non-TC-compatible lenses: The lens does not detect the TC and just reports its own f-stop. AF may still work, because the camera doesn't know about the true f-stop, and tries to AF even if the combination is outside the specs.

Kenko DGX: Unlike the above TCs, the DGX manipulates the communication between the lens and the body so that the f-stop is always reported correctly for the combination, and so that AF is retained even if the combination is above f/5.6. From your and others observations that f/8 is reported but AF still works, my guess is that wide-open f-stop and used f-stop is reported separately and the camera looks at the wide-open f-stop to determine if it should try to AF.
 
With a non-reporting TC AF will work at final apertures slower than f5.6 - but only if your definition of the word 'work' is 'attempt to focus, sometimes succeeding in very good light, but normally failing after a lot of hunting'.

If AF works with a 300f4 and a 2xTC on a non-1D then please show us a couple of birds in flight images.

Note how the 1Dx doesn't claim to be able to work slower than f5.6.
 
hollis_f said:
With a non-reporting TC AF will work at final apertures slower than f5.6 - but only if your definition of the word 'work' is 'attempt to focus, sometimes succeeding in very good light, but normally failing after a lot of hunting'.

If AF works with a 300f4 and a 2xTC on a non-1D then please show us a couple of birds in flight images.

Note how the 1Dx doesn't claim to be able to work slower than f5.6.
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As this is not my definition of "work" but seemingly yours, I regret that I must politely decline this obviously impossible task.
 
footman said:
The TC arrived today so I stuck it on a 5DII with the 300 f4 to see how MF would work. I was somewhat taken aback when it AF'd perfectly and I took some shots.
To confirm this I changed the body for a 7D, it still worked! I changed the lens to a 70-200 F4 and it AF'd with that. It failed on a 400 f5.6.
Click to expand...

footman said:
As this is not my definition of "work" but seemingly yours, I regret that I must politely decline this obviously impossible task.
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So, the AF works 'perfectly', but getting BiF shots is impossible?
 
footman said:
Good grief, give it a rest.
I apologise for my poor etymology. I was merely pointing out that I was surprised that it happened at all, I just wasn't expecting it.
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The problem is that others are going to read how AF works 'perfectly' and possibly splash out a load of cash. Only to find that their money has been wasted.
 
So just to confirm...........:thinking: would an all singing and dancing canon 1.4 mkiii tc work perfectly (still autofocus) with a sigma 150-500 ? To cut a long story short, im thinking of getting some L glass in the future (possibly 28-300 or 70-200) but would equally welcome a little more reach with my sigma. Sorry to hijack thread a bit ;)

Thanks

Coley
 
Coley. said:
So just to confirm...........:thinking: would an all singing and dancing canon 1.4 mkiii tc work perfectly (still autofocus) with a sigma 150-500 ? To cut a long story short, im thinking of getting some L glass in the future (possibly 28-300 or 70-200) but would equally welcome a little more reach with my sigma. Sorry to hijack thread a bit ;)

Thanks

Coley
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NO (unless you have a 1D body).......... Canon TCs (MKI, II or III) will only work as stated above, autofocus upto f5.6 for non 1D series bodies and f8 (centre focus point) for 1D series camera's.

The Kenko 1.4x MKIII would probably work, but the sigma 150-500mm is already a slow lens, losing another f-stop would mean, near perfect light conditions to get anything worth while image wise.

As for the canon 28-300mm f3.5-5.6, not a great lens, probably better off getting a 100-400mm f4.5-5.6
 
Coley. said:
So just to confirm...........:thinking: would an all singing and dancing canon 1.4 mkiii tc work perfectly (still autofocus) with a sigma 150-500 ? To cut a long story short, im thinking of getting some L glass in the future (possibly 28-300 or 70-200) but would equally welcome a little more reach with my sigma. Sorry to hijack thread a bit ;)

Thanks

Coley
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I don't believe that the canon TCs will fit the sigma, as they have a protruding front element, and therefore will only fit some canon lenses.

The Kenko and Sigma TCs should pretty much fit any EF fitment lens.

IIRC Canon state that 1D bodies will autofocus up to f/8 but none 1D bodies may not. That means in some cases with the correct lens and camera combination you may still retain autofocus but Canon cannot guarantee it. Which is way they don't say that it will.
 
Andy_S_T said:
IIRC Canon state that 1D bodies will autofocus up to f/8 but none 1D bodies may not. That means in some cases with the correct lens and camera combination you may still retain autofocus but Canon cannot guarantee it. Which is way they don't say that it will.
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Nope. They don't say "it will work". They don't even say "it may work". That's because it won't work, not even a little bit - at least not with all Canon gear.

Canon will not make any claims as to the abilities of third-party equipment. They will only comment on their own TCs. If you use a Canon TC on a Canon camera that is not a 1D, or is a 1Dx, then AF will not work if the resulting aperture is slower that f5.6. It won't even try to work. AF will be disabled.

Why do Canon disable AF on lens/TC combinations slower than f5.6? Because it doesn't work properly. If they didn't disable it then they'd have thousands of support calls from people complaining that it doesn't work.
 
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