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Canon 100-400MM with Canon 1.4 TC

J. Harrington USA (Massachusetts) , Sep 03, 2006; 07:51 p.m.

I'll soon be purchasing the Canon 100-400MM L IS. I may also purchase the Canon 1.4 TC. What should I expect as far as auto-focus and IS functionality. I've searched photo.net but did not find specifics on this combination. I understand AF would work only in bright situations and sharpness would be compromised with the TC.

They'd be used on my 10D mostly for wildlife, birds, other nature photography, the moon etc. I own a solid but old and heavy tripod.

Someday, the lenses may be used on a 5D or its replacement.

If anyone can point to images made with this lens and 1.4 TC that would be great.

Thanks in advance, J.


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Professor K. , Sep 03, 2006; 08:22 p.m.

On a 10D the camera will shut down AF with a Canon converter if the maximum effective aperture is less than 5.6. The IS should work just fine.

Steve Dunn , Sep 03, 2006; 08:34 p.m.

AF will not work at all unless you tape over the extra pins; this is true for both your 10D and for a 5D. Only the 45-point AF bodies will retain AF with this combination, and even at that, only with the central AF point. If you tape over the pins, then it will be more like how you described it: AF will try to work, and it may work some of the time, but definitely won't work in some situation in which it would have worked without the TC.

IS will work properly with all EOS DSLRs as well as all EOS film SLRs released in the last decade or so.

Bob Keefer , Sep 03, 2006; 10:08 p.m.

Great lens but a bad combo with the 1.4. As you say, sharpness is "compromised" -- another word might be "terrible."

As the other posters mention, auto-focus won't work without the tape trick. IS will.

Try before you buy.

Peter Lyons , Sep 03, 2006; 10:27 p.m.

I own that lens and am happy with it. IMO it can deliver tack-sharp images if technique and focus are perfect. It's really a very long lens already on a cropped-sensor body like your 10D. If you want more length still and are really concerned with sharpness, consider the 400 5.6 L. You'll lose IS, but primes are sharper than zooms. Plus it's a few hundred bucks less expensive. In "The Art of Bird Photography (1998), Arthur Morris writes, "The Canon EF 400 f/5.6L lens is my absolute favorite." The guy is really good. So I'd consider that the strongest of endorsements.

Alistair Windsor , Sep 03, 2006; 11:16 p.m.


Arthur Morris is as concerned with AF as with sharpness. I use a 300/4 IS + 1.4x TC for my long lens. Optically is quite a bit better than the 100-400 and, in PhotoZone testing (1.6x crop factor) was sharper than the 400/5.6 in the centre and only slightly worse than the prime in the borders. However AF performance is sluggish with the extender and not really appropriate for birds on the wing.

The 100-400 is perhaps the ideal Canon lens for safari photography where you have animals of different sizes appearing at unexpected distances (one earlier poster referred to this lens as his "zoo" lens). If you anticipate always using the long end of the zoom (which implies you have something to cover the rest of the range) then get the 300/4 IS + 1.4x extender or the 400/5.6 (they are similar prices and cheaper than the 100-400). You can use the extender with the 400/5.6 but without the taping trick you won't maintain AF.

I know a couple of people with 100-400 IS lenses and they really like them but non of them use the 1.4x with it. Anecdotally I know of people who use this combination and are satisfied with it (and people who were not even satisfies with the performance at 400mm). I wouldn't expect much from the AF even with taped pins.

That long spiel can probably be taken as advice against getting the 1.4x for the 100-400. I have the extender and use it on two of my lenses (70-200/4 and 300/4 IS) and love the optical performance. Both lenses are exceptionally sharp to begin with.

If you go to pbase you can find pictures with this combination. Here is one


but there is no original so it is of little use in examining sharpness.

Mark Nagel , Sep 04, 2006; 01:19 a.m.

I use my 100-400 w/1.4x for moon shots. At f/11-f/16 I don't see much degradation. Its better than without the 1.4x at f/8 magnified to match the size in photoshop. Of course this is with a tripod, mirror lock up and pretty slow shutter, all impractical for birds. Other than those shots, my 1.4x sits in my bag collecting dust.


Professor K. , Sep 04, 2006; 09:44 a.m.

"You can use the extender with the 400/5.6 but without the taping trick you won't maintain AF." I've tried that with a 10D and a 20D. Doesn't work. Camera cannot obtain proper focus.

Louise Heusinkveld , Sep 04, 2006; 11:02 a.m.

I thought I had read some time ago that the "pro" versions of the 1.4 converter by either Kenko or Tamron had better functionality for AF than the Canon, and are also reasonably sharp. Am I wrong? The Tamron 7 element 1.4 was to be my next purchase...

Mark Chappell , Sep 04, 2006; 11:27 a.m.

I have this lens, and while my copy is quite sharp at focal lengths of ~ 300 mm or less, and pretty good at 300-400 mm if stopped down just a little, I did not like the results with a 1.4X at all. Perhaps if stopped down to f11-16 it would be OK, but for a lot of wildlife work, that's pretty slow.

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