EF 100-400 and Canon Extenders

Can anyone tell me plz
is the canon extender x1.4 work fine auto focus with this lens on the 7D ?
or it will be manual focus ?
i want to know before buying this extender
Thanks

It should be manual only, on the long end. I believe only the 1D series is capable of AF on f8 which is the f-stop you would be with the 100400 + 1.4 TC. I have read that some of the sigma TC will allow AF in bright conditions, but not reliably.

Thanks a lot

you can use the tape trick to gain auto focus. You can read more from the link below, there is also a link to a website (bottom of post) that shows you how to do it.

http://www.flickr.com/​photos/ehambrick/59603​89495/

If you plan on using the 1.4x III extender on this lens i suggest you lower your expectations. Auto focus does NOT work unless you do the "Tape trick" which you tape 3 pins on the lens that attaches to the body, which tricks the camera into thinking there is not extender on and you can use the center focus only.

<b>You HAVE to use this setup on sunny days</b>. The photo above was pushing it, late in the day, but i was able to auto focus with that light. Auto focus is SLOW and very annoying. It may take 5 to 10 seconds to lock on, so if you are doing wildlife it can easily make you miss shots.. with that being said i was able to get some awesome action shots and wildlife shots with the extender and tape trick. For example, you can see below a Great Blue Heron fishing while a Cormorant drifts by. In great light you will be able to focus quickly, only noticing a slight delay.

<b>So with the 1.4x extender on my full frame body and the 100-400mm</b>, that gives me 140-560mm. It is long enough to hand held without too much lose of quality. If you were shooting on a cropped camera like a 7D or my back up, a 40D, i have seen people report problems with the photos being blurry while hand held...

IMAGE LINK: http://www.flickr.com/​photos/ehambrick/59603​89495/

Thanks internets
for all the info

I don't have a 100-400L. While using a 1.4x TC with it should make AF not work- and you might be able to pull off autofocus with the tape trick- there are other tricks that can help.
1. You can pre-focus- get it in the neighborhood.
2. If you have a focus limiter ( Don't have a 100-400L- so I don't know if it does )- use it.
3. Use live-view. You probably won't need the tape trick to do this. Pre-focusing might help. A focus limiter- if you got one- helps.

It blows my mind, how many people are too lazy too search anything. Although the search on this site is pretty lame, there are 100's of threads regarding this, filters, 50/1.8 vs 50/1.4, 24-105 vs. 24-70, etc. etc.

I, also use the tape trick with a 5D Mkll. It works, and as mentioned by others, slow.
In even slightly shaded conditions, it can be very iffy to no worky.

Same here, the tape trick does the business. I don't find it slow in shady conditions, it just keeps going.

I've used my Kenko Pro300 DGX 1.4x converter on a Canon 100-400 L and retained AF on my 550D, 60D, 7D, 5D2 and 5D3. The DGX version doesn't need any pins taping and it reports correctly in the EXIF too. It slowed down the AF very slightly and it AF'd in all but dull light and there was negligable loss in IQ too.

modchild wrote in post #14818085
I've used my Kenko Pro300 DGX 1.4x converter on a Canon 100-400 L and retained AF on my 550D, 60D, 7D, 5D2 and 5D3. The DGX version doesn't need any pins taping and it reports correctly in the EXIF too. It slowed down the AF very slightly and it AF'd in all but dull light and there was negligable loss in IQ too.

Good to hear- yours is one of the most positive reports on this. My Canon 400mm f/5.6L was pretty good with that Kenko TC, I am hesitant to push my luck on a 100-400L, but it sounds like I should maybe give it a shot with my 7D.