topic Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender in EF & RF Lenses

Auto focus w/ EF100-400L IS USM & 1.4 Extender

Bigdawg — Wed, 26 Jun 2013 04:19:15 GMT

The lens manual states I should be able to a/f with these new lenses using single point focus. I can't seem to get it to work (tried full auto -grn box - and P modes). I want a/f for fast moving wild life shots (I.e. birds). I have a 7D body.

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

trulandphoto — Wed, 26 Jun 2013 10:24:12 GMT

I believe the 7D will only phase detect autofocus with lenses having a maximum aperture of f/5.6 or greater (greater aperture opening, lower number). With the 1.4X extender the zoom becomes a maximum f/8 aperture lens. Contrast detect AF will work (live view) but it will be slow and not suitable for "fast moving wildlife."

A lens would have to have a maximum aperture of at least f/4 to autofocus with the 1.4X extender on a 7D.

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

cicopo — Wed, 26 Jun 2013 11:50:20 GMT

To the best of my knowledge the only bodies which can AF at f 8.0 are the 1 series bodies & the 5D3 with the new firmware installed. Even then in most cases it will be slower than usual.

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

WahoGT — Wed, 26 Jun 2013 13:38:25 GMT

You can try the "tape" trick on the lens connection pins to fool the camera into not knowing what f-stop youre shooting at, thus it will try to AF... but performance may be spotty at best. Not exactly the ideal setup for fast moving subjects.

Good luck!

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

Bigdawg — Wed, 26 Jun 2013 14:19:48 GMT

Thanks, I appreciate the responses. I'm just getting back into photography after a couple of decades. I understand the issue and will have to either revert to the 100-400 for those fast action shots, or learn to manually focus (i.e. improve my skill). I guess that's part of the price you pay for getting a $2.3K setup versus a $12K (new 100-400 f2.8 lens) setup.

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

amfoto1 — Wed, 26 Jun 2013 18:07:58 GMT

"...I'm just getting back into photography after a couple of decades. I understand the issue and will have to either revert to the 100-400 for those fast action shots, or learn to manually focus (i.e. improve my skill). I guess that's part of the price you pay for getting a $2.3K setup versus a $12K (new 100-400 f2.8 lens) setup."

Um, I think you are refering to the new 200-400/4L IS 1.4X that lists for around $12K US. Heck of a lens, but it's not f2.8 and the focal length range is 200-400. And it has a built-in, carefully matched 1.4X teleconverter, so no need for one of those. With the 1.4X engaged, it's an effective 280-560mm f5.6 lens. Even at it's high price, IMO it's a bargain. I figure for most practical purposes it might replace around $20,000 to $40,000 worth of prime lenses (200, 300, 400 and 600mm), which would be impossible to carry around without a pack mule.

Your 100-400 might see more image quality loss than you like with a teleconverter on it... or you may be happy with it. You can get AF to at least try, though, by using the trick (already mentioned above) taping up a couple of the electronic contacts on the lens or teleconverter. Do a Google search, I'm sure you'll find some info online about how to tape up the contacts. It's an old trick that some people use to fool the camera into not recognizing that the teleconverter is there and still trying to AF. Depending upon the light conditions, subject detail/contrast, distances and other factors, the AF may work fine or might not work particularly well... In some more challenging conditions it is likelly to be slow or hunt or completely fail to achieve focus. OTOH, it's easy enough to try and might work for you.

I'm an old manual focus shooter from way back when, too. I resisted AF until I switched to Canon in 2001. Now that I've learned to use it well, I'll certainly never go back! AF is far faster and more accurate than I ever was, trying to focus manually (and I was pretty darned good). I'm not the only one, either. I've got an old Thomas Mangelsen print that dates back to his early days shooting with manual focus cameras, where it's obvious he wasn't any better than me manual focusing! I keep it framed on the wall to remind me that there's more to a fine, salable image than a lot of the bloggers today would have you think, reading all posts the obsessing about lens sharpness, focus testing and near impossible, pixel-level perfection they all seem to be seeking.

Re: Auto focus w/ EF100-400L IS USM & 1.4 Extender

isawa — Thu, 04 Jul 2013 18:23:21 GMT

I shoot 7D with 100-400mm lens and 70-200mm F/4 lens. I have used 100-400 with EF 2.0 III extender. Under the right condition I can auto-focus fine using Live Mode. I do have all focus options programmed in, but I normally use SPOT focus mode with these lenses. I do switch to the other focus mode depending on occasion.

In the past, I did have some focus problem with 100-400 on 7D. The image was often out of focus especially when the lens was zoomed all the way out to 400. I took both LP-E6 battery and C1616 3 "clock battery", and left them out over an hour, actually overnight. That did the hard reset, and auto-focus problem was completely fixed.