7D focus with extender

My 50D will not auto focus with an EF1.4 X11 extender when using my EF400L f5.6 lens becoming f8 ( I know there is a way to cheat by taping terminals )

Does anyone use this lens set up on the new 7D if so will the camera focus without cheating and how good is it?

There is no way any non 1 series camera would AF beyond f5.6 because as soon as the camera detects it then it electronically shuts down the AF. There are only two ways to acheive AF at f8:
1) Tape the three pins on a reporting tc
2) Use a non reporting tc

In these instances the camera/lens combo will attempt to AF because the Camera does not know of the Tc - results will be variable depending on light and contrast.

If you want to judge the quality with a tc attached just manual focus a few shots which will give you an indication of the IQ. For what it is worth, the 400/5.6 takes a 1.4tc very well, especially if you can stop down one (which means f11).

Hi Roy
Thanks for your advise, as I had thought but needed confirmation. Darn, just going to have to dig deeper into my pocket and buy a new D1MK1V I guess.

luckyart60 wrote in post #9156008
Hi Roy
Thanks for your advise, as I had thought but needed confirmation. Darn, just going to have to dig deeper into my pocket and buy a new D1MK1V I guess.

It would be cheaper to buy a faster lens
I used a 400/5.6 for three years and it is a cracking lens but a few months ago I changed to a 300/2.8 which I often use with a 2x tc (600/5.6) could not be happier. The performance with a 2x has far exceeded my expectations and full AF on the 7D.

Interesting point of view certainly worth considering.
At the moment I usually have my 50D set up with my 500 Lens plus 1.4 tc.(giving f/5.6) focusing can be slow when jumping from different focal lenghts, even sometimes i need to help it out by roughly getting a manual focus and then let the camera take over. On several occasions I missed a good shot of an important bird.
I have my second camera 1D set up with my 400 lens plus 1.4 tc for BIF hand held which is so fast to focus and gives me good results.

I find that with the 300/2.8 and 2x tc that using a focus limiter makes a big difference to AF speed.

Roy C wrote in post #9156406
I find that with the 300/2.8 and 2x tc that using a focus limiter makes a big difference to AF speed.

But for better or worse?

artyman wrote in post #9156477
But for better or worse?

Far better of course because you have limited the focusing distance.

The focus limiter is built in to the 300 f2.8, It is turned on or off with a switch on the lens.

Hi Roy
So if you step down below f/5.6 does that mean you loose auto focus?

luckyart60 wrote in post #9164569
Hi Roy
So if you step down below f/5.6 does that mean you loose auto focus?

No, for AF purposes a camera always opens the lens right up, only stopping down at the point when the shot is taken. This is no different for any camera/lens combo.