Disappointed with 1.4 Extender on 400mm

I love the canon 400mm prime on the 7D2 body. Auto-focus speed is increadable for action photography. Was so disappointed with the AF speed with the canon 1.4 III extender added. It slowed down considerably and did much more hunting to find focus compared to no extender. Is there anything that can be done to increase AF speed. I"m shooting wildlife in natural light. Has anyone else noticed the same significant decrease in AF speed.

I have the same setup as you, and my experience has been the same. I've found the extender usable for perched or wading birds, but terrible for flight shots or other action. I had pretty much stopped using it for a couple of years, but tried it earlier this year when I felt I could use the extra reach shooting a male harrier. Out of maybe 100 shots I only got several keepers - I would have been better off leaving it off and just cropping tighter.

Larry Johnson wrote in post #19104085
Disappointed with 1.4 Extender on 400mm
I love the canon 400mm prime on the 7D2 body. Auto-focus speed is incredible for action photography. Was so disappointed with the AF speed with the canon 1.4 III extender added. It slowed down considerably and did much more hunting to find focus compared to no extender. Is there anything that can be done to increase AF speed. I"m shooting wildlife in natural light. Has anyone else noticed the same significant decrease in AF speed.

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It would help if you told us which one of the Canon 400mm prime lenses you are talking about.

I've used the Canon 400 f2.8 with the 1.4 and it worked marvelously with the 1.4 extender on it, no matter which body it was on. . It focused just as fast and accurately with the extender as it did without it. . At least I couldn't tell the difference. . And the image quality was just as good with the extender as it was without it - can not tell any difference at all, even when pixel peeping at way beyond 100% pixel views.

I've also used the Canon 400mm f5.6 with the 1.4 extender, and did not like it at all. . It did slow autofocus down a little, and the image quality was ever so slightly poorer with the extender than it was without it. . The 400mm f5.6 and the 1.4 extender are a poor combination, in my experience, because it isn't exactly as good in every way as the naked lens without the extender.

So based on my experience, if you are using the 1.4 extender with the f2.8 lens, and it is not working flawlessly, then something is probably wrong with one of the pieces of gear involved.

If you are using the extender with the f5.6 lens, and it is not working flawlessly in every way, then I think that there may be nothing wrong with the gear, and that you should probably expect some slight compromises to come into play when you use the extender.

I haven't used the 1.4 extender with either of Canon's 400mm f4 lenses, so if that is the lens you are talking about, I don't have any experiences to share with you. . Sorry.

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I will serving the above very detailed comment. If your lens is the f5.6 version, you will struggle with BIF when used with TCs.

I believe 7D2 gives you only the centre focus point when you attach a TC to a 5.6 lens. That in itself is problematic to track erratic/fast movements

Remember your camera needs light to focus, it's why the aperture is always set to it's widest point when focusing before stopping down if needed to take the photo.

Extenders increase the lenses focal length, but they do not change the size of the aperture. This means using a 1.4x extender on a lens with a maximum aperture of F2.8 makes an F4, and a lens F4 becomes a F5.6, and a F5.6 becomes an F8.

While the 7D can focus really well at F2.8 and F4, at F5.6 it will be starting to struggle, and while it can focus at F8 (a lot of earlier cameras couldn't) it will be really struggling to find an area of sufficient contrast with the limited light it has to work with.

Larry Johnson wrote in post #19104085
I love the canon 400mm prime on the 7D2 body. Auto-focus speed is increadable for action photography. Was so disappointed with the AF speed with the canon 1.4 III extender added. It slowed down considerably and did much more hunting to find focus compared to no extender. Is there anything that can be done to increase AF speed. I"m shooting wildlife in natural light. Has anyone else noticed the same significant decrease in AF speed.

F/8 is not a favorable open f-ratio for AF on the 7D2 in OVF mode. OVF AF abilities are marginal at f/8 in many cameras, especially older ones, even if they officially support f/8. You need good contrast and light, and minimal confusion of depths, to get reliable AF.

tomj wrote in post #19104100
I have the same setup as you, and my experience has been the same. I've found the extender usable for perched or wading birds, but terrible for flight shots or other action. I had pretty much stopped using it for a couple of years, but tried it earlier this year when I felt I could use the extra reach shooting a male harrier. Out of maybe 100 shots I only got several keepers - I would have been better off leaving it off and just cropping tighter.

... or using Live view. Many cameras have better f/8 AF in Live view, but that makes operation with narrow angles of view very difficult, without a loupe, and most older cameras have significant LCD lag.

John Sheehy wrote in post #19104221
... or using Live view. Many cameras have better f/8 AF in Live view, but that makes operation with narrow angles of view very difficult, without a loupe, and most older cameras have significant LCD lag.

I've used live view in difficult focusing situations of relatively static subjects, but for me at least, it's impossible for BIF, which was the case with the harrier I mentioned.

Tom Reichner wrote in post #19104124
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It would help if you told us which one of the Canon 400mm prime lenses you are talking about.
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He has the 5.6 version in his gear list at the bottom of his post.

Moppie wrote in post #19104188
Remember your camera needs light to focus, it's why the aperture is always set to it's widest point when focusing before stopping down if needed to take the photo.

Extenders increase the lenses focal length, but they do not change the size of the aperture. This means using a 1.4x extender on a lens with a maximum aperture of F2.8 makes an F4, and a lens F4 becomes a F5.6, and a F5.6 becomes an F8.

While the 7D can focus really well at F2.8 and F4, at F5.6 it will be starting to struggle, and while it can focus at F8 (a lot of earlier cameras couldn't) it will be really struggling to find an area of sufficient contrast with the limited light it has to work with.

It goes beyond the lower light levels with a higher open f-ratio. The 7D2 will AF very easily at f/5.6 on a B&W pattern in pretty low light, but if you use f/11, no matter how much you increase the illumination, you still won't get focus. Most (if not all) of my DSLRs can focus at f/8, even if they're not supposed to (if you trick them), even indoors with the blinds closed, but none will focus out in the sun at f/11, although f/9 has worked marginally (f/6.3 + 1.4x). In OVF AF modes, DSLRs seem to fall off a cliff at some point between f/8 and f/11, in the ability to focus at all, no matter how much light. Most types of AF except pure contrast-detect sensor-based AF rely on bundles of light coming to focus at various angles, which is where f-ratios come into play. Even for contrast-detect, though, diffraction and aberrations can make the assessment of focus slower.

Hey, thanks for all the replies. I didn't realize that anyone had replied because I didn't receive and email notice like I do for posts that I didn't create. At any rate, I have the f5.6 and looks like others have experienced the same slow focus condition. Such a shame. Would a 1D body produce the same problem, or is it a lens issue.

You will have better success with 1Dx and up. I don’t know about the older 1D bodies; never tried 5.6 lens with a TC on my 1D iv.

Larry Johnson wrote in post #19104489
Hey, thanks for all the replies. I didn't realize that anyone had replied because I didn't receive and email notice like I do for posts that I didn't create. At any rate, I have the f5.6 and looks like others have experienced the same slow focus condition. Such a shame. Would a 1D body produce the same problem, or is it a lens issue.

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The focusing deficiencies that I described in my previous post occurred on every body I tried it with. . This includes the 1D Mark 4. When you have a slow lens with a small aperture and then you put an extender on it, you can't reasonably expect fast focus tracking like you would get with no extender.

It would be interesting to see how the 400mm f5.6 and the 1.4 extender perform on one of the two new mirrorless bodies, the R6 and the R5. . I think that because they do focusing based on sensor readout, that their focusing systems aren't limited by light the way contrast-detect focusing systems are. . So maybe with one of those cameras you would get perfectly fast and accurate autofocus, despite the fact that you would be using an adaptor to mount the extender to the camera.


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All focusing systems are impacted by the level of light. The difference is a contrast detect systems becomes less able to quick focus and then just stops working altogether, while a phase detect (like in mirrorless cameras) just gets slower and takes longer to focus.

A 1Dx in theory would work better, but even at F8 it's not going to perform as well it does it at larger apertures. An R5 or R6 would also keep working at F8, but again it's ability to find focus will slow down.

Moppie wrote in post #19104599
A 1Dx in theory would work better,

Mark II and especially III for sure, but I doubt that the original 1Dx is much (if any) better at f/8 in marginal conditions. In perfect conditions, like a BIF against deep blue sky, it should drive the AF faster, though.