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Bought a kenko 1.4 converter for mine sigma 150mm. Thought It also would be nice to use on the canon 500mm f4.5 On the internet I saw a lot of people who used this kenko converter on a F 4.5 or F 5.6 lens and still have autofocus.
No I tried it, but I don't have autofocus. Does anyone know why?
If you have a camera other than the 1D then you will either have to use a non reporting teleconverter or tape the pins on the Kenko to allow AF on the Canon 500mm f4.5 as with the 1.4x the aperture becomes f6.3 and most Canon cameras only AF up to f5.6
It could depend on the versions of the converters too. The newer ones will have a better chance of reporting the information correctly allowing the camera to limit the autofocus.
I have a Tamron 1.4x that's non-reporting for the same 500L f4.5 (with a 40D and 50D).
It's the C-AF1 MC4 - got it 2 or 3 years ago, so they may have a new version that does report (which may be the problem with your Kenko TC, too).
I had good success with the Kenko 1.4x DGX
It reports the right EXIF data but still allows lenses to AF over f5.6 (as if it had the pins taped)
