1.4 tele question on 400 5.6

Thinking about buying a 1.4 teleconverter for my 400 5.6. Is there a big difference between the Kenko 300 and the canon version, other than cost? Some say use this lens on my 60D for extra reach but I love the iso performance of the 5D3 to much.

On another forum (which currently seems to be down, so I can't double-check at the moment), someone mentioned having issues using AutoFocus with an old Kenko converter on a 6D (even when wide open). Obviously, there are quite a few parameters here: how old was the Kenko, will the same issues occur on a 60D or 5D, etc... But in terms of compatibility, it would be safer to get the Canon. By the way, AF will also not work on most Canon bodies beyond f5.6 unless you tape off the pins (and even then AF can be quite inefficient). The 5D3 with the latest firmware allows you to go to f8 without taped off pins and it still focuses well.

Personally, I would go for the Canon extender + the 5D3. The externder might cost a little more, but I have learned (not just in photography) that a little more money for a lot more quality (in terms of build, usability, compatibility, versatility, ...) pays dividends in the long term.

CHUCK A wrote in post #16139396
Thinking about buying a 1.4 teleconverter for my 400 5.6. Is there a big difference between the Kenko 300 and the canon version, other than cost? Some say use this lens on my 60D for extra reach but I love the iso performance of the 5D3 to much.

The whole idea of using a 400mm lens is reach. I have crop and FF cameras as well, but I always use the 400mm on the crop. I only have the Canon 1.4X. It works fine, but you lose auto focus. That so called taping trick to gain AF didn't work for me.

I believe I read where the 5DIII and the firmware update allows AF to f/8, so the 400L plus the 1.4X should be fine (when using the center-point). On the 60D no AF without the tape trick. With the tape trick, the AF on my zoom is reliable only in great light.

On a 5DIII with the 1.4X gives 560mm f/8. On the 60D gives a FOV live a 640mm and AF. I'd probably use the 60D, depending on the subject and lighting.

I do not have the 400L, so the rest is based on my lens lineup. The Kenko and Canon 1.4X MKII both function (AF performance and IQ) about the same with a slight edge to the Canon (which might be just copy variance). Build in the Kenko is excellent, but in the Canon it is way better. It is like comparing a consumer lens build to an L lens build.

Advantage to the Canon is build quality (and possibly slightly better performance). Disadvantages cost and can only be used on certain lenses (Of Canons current lineup -135L and longer plus the 70-200Ls).

Advantage Kenko is cost and it fits any EF (not EF-S) lens. The newest Kenko (which I don't have) is supposed to have new/better wiring and circuitry for better electronic connect-ability. (Better AF performance?)