1.4 extender on a 40D with 100-400? (1 Viewer)

Hi guys,
I know the topic of will it won't it autofocus has been done to death, but this mainly refers to the Kenko 1.4 DG .
My question is, on a 40D with a 100-400 lens, does anyone have any info on whether the genuine Canon 1.4 extender works with well this combo ?
Thanks for any enlightenment

I presume you are asking if the Canon converter will enable auto-focus with pins taped down? Since Canon have sought to prevent auto-focusing with the 40D and 1.4 converters it would seem reasonable to assume that performance with theirs will be as with other TCs.

Yes, I know that it would probably have to be with taped pins and presumably at F5.6 the fastest that lens will allow..

Users have reported that the 100-400 and 40D combo with a taped tc (does not matter which) AF is almost a non starter when using the centre focus point - if you use one the the outer focus points things get a lot better although far from great
I have used the 400/5.6 prime with both the Canon and Kenko pro converters (pins taped) and the AF performance is about the same whichever converters you use.

For the record all Canon xxxD and xxD Cameras will only AF up to f5.6 - when you add a 1.4 tc this adds a stop which takes you to f8. Taping the pins is used to fool the Camera into not knowing its there so the Camera will attempt to AF as it thinks it is still at f5.6.
Using a cheaper non reporting converter gives the same effect without the need to tape the pins but you are still trying to AF at, effectively f8, when the Cameras AF system is not designed to do so. It would seem that a non reporting tc actually works better but I have not tried this myself.
Hope this helps.

Thanks Roy . Its a shame that Canon decided to go this route. I wish there was a decent way around it, that saves having to buy a longer lens !

nikovich said:

Thanks Roy . Its a shame that Canon decided to go this route. I wish there was a decent way around it, that saves having to buy a longer lens !

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I use my 400/5.6 with a taped tc on the 40D on a regular basis and am very please with the results BUT I always use the combo on a tripod so I do not mind resorting to MF at times if the light is not great or the subject has not got enough contrast. The point is that manual focussing or using manual to get roughly in focus before letting the AF finish the job is a lot easier on a tripod than trying to do it hand held.