Canon 100-400mm Issues

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    Abigail Blackstone

    Hello folks! I own a Canon 100-400mm IS L first generation lens. I have had it for about a year and a half. I took a trip last weekend and took lots of pictures on the way, I was very disappointed when I looked at them on my computer and discovered that nearly all were blurry. Rather than motion blur, these seem to always be just outside the plane of focus. I did use a tripod for some, with the IS off, for others I hand held with the IS on. For many I was not zoomed out to the full 400mm, but even those were not crisp and sharp like I have grown accustomed to with this lens. Do any of you have any suggestions?

    Ezra Morley

    Good question! Large telephoto lenses seem to have a tendency to “disappoint” users in certain circumstances. I’ve actually been doing some research recently on 400mm lenses, so I’ve seen lot’s of photos taken at 400mm which were anything but stellar.

    My best guess would be autofocus issues. Seeing as it’s one of Canon’s prestigious “L” series, it definitely shouldn’t have any sharpness problems! Were the pictures taken in low-light conditions by any chance?

    That said, without being able to see what “problems” you are seeing, it’s rather hard to diagnose the problems. If you don’t mind, could you post a few samples? Ideally, I’d like to see the originals, at full resolution, (it’s very hard, if not impossible to judge sharpness on a resized/resampled photo). If they are RAW files, and you use Lightroom, then you can export at lower JPG quality (77) to save on bandwidth.

    Please note that this forum only supports files up to 2MB in size, so an original photo file likely will be too large. Probably your best option is to use another service such as Dropbox or Google Drive, or even Flickr, and then post a link to them here on the forum.


    The 100-400 (1st generation) is known for needing afma (auto-focus micro-adjustment) and for having a lot of sample variation. It might be worth looking into that. On the other hand, if you are used to getting sharp images with that lens on that body, it sounds less likely. Are you indeed using the same camera body as you were? You say that they seem to all be outside the plane of focus, and that does sound like a focus problem. Afma can fix that, if it’s not too far off. Read up on afma before trying it, as it can make things worse, apparently (never did it myself.
    Try doing some test shots in a controlled setup to see if it’s *possible* to get the image quality your used to seeing. Tripod, mirror lockup, remote release, immobile test target, live-view focus, etc. (Also test your autofocus while your at it) If you still can’t get what you think it should be giving you, then it might have gotten dis-aligned, damaged, or something and might need a repair. The 100-400 with it’s trombone-style zoom has the reputation of getting a lot of dust sucked into it, so it might be worth a check, although it would take a *lot* of dust to affect image quality. Just shine a flashlight in the camera end and look into it from the opposite end and everything will become apparent.
    Good luck with that!

    Abigail Blackstone

    Thank you for your suggestions, I will give them a try. I have been shooting with the same camera body, I also took the photos in plenty of light. It is odd, sometimes I will get consistently out of focus pictures, and then randomly, a fantastic shot.

    This picture I took at 400mm, from a tripod with the IS off, it was on a bright day so my shutter speed was 1/1000. I did have to downgrade the file to be able to upload it, I am not familiar with how to use my google drive to show the picture.


    Ezra Morley

    Unfortunately, Canon’s cheapo Rebel T3 doesn’t have the auto-focus micro-adjustment feature, that is reserved for their more expensive cameras.

    I wonder if @nasa wasn’t onto something about it’s being dropped, or mis-aligned somehow. Otherwise, remember that the Rebel T3 is only a cheap entry level DSLR, so you can’t expect world shattering AF. On the other hand, I would expect it to focus at least 50% of the time! One thing to remember…

    The Rebel T3 only has 1 cross-type focus point, the one in the middle. That one is the most accurate/sensitive, so if you always use that one, you might get better results. When I’m using a telephoto lens, I often take multiple shots of the same subject, focusing each time. That should increase the odds of your getting at least one photo in focus.

    BTW, I like that photo you posted, there’s certainly no focusing issues with that one!

    If you have Google Drive installed on your computer, you can just copy the picture to your Google Drive folder and allow it to upload, then right-click on your photo in your Google Drive folder, and select “Google Drive” > “Share…” That should open a dialog box where it asks you to put in the e-mail address of the person to share it with. Instead inputting an e-mail address, click on “Get shareable link” in the upper right hand corner of the box. Just copy that link and paste it into your post here on the forum, and that should do it!

    Abigail Blackstone

    I do use the middle focusing point, it is easier to use just one point when I am trying to get a bird’s eye finely in focus.

    As for the picture I posted, that is perhaps in focus, but not crisp. The glass in the L lens is or was great, I could see every detail in feathers. I will post a few good pictures so you can compare. Here is the google drive link:

    That was my next question. Is it my camera body? I would much rather it be that than my lens, I spent a lot less on it. I got the body new in November of 2011, so it has seen a lot of use. Do you think that a better body, say the 7D mark ii would fix my focusing errors?

    Thank you so much for all of your help!


    James Staddon

    Hey, welcome to the forums, @AbigailBlackstone!

    I just requested access to the Google Drive folder for [email protected]. You can either grant access, or you could make the folder public so anyone and everyone who clicks on the link can view it.

    Looking forward to seeing the pictures in that folder. The initial image that was uploaded didn’t seem to retain enough quality at 100% to be able to make much of a comment when we’re splitting feathers over sharpness. 🙂

    As an L user, I would fault the Rebel T3 before I did the 100-400mm.

    • This reply was modified 50 years, 11 months ago by .
    Ezra Morley

    I also requested access as [email protected] As @JamesStaddon said, you could just make it Public so anyone can view them.

    I think I would agree with your opinion James, about the T3, but that still doesn’t explain why every once in a while you get a perfectly good shot!

    , you would likely see an improvement by upgrading to the 7D Mk II. It’s Canon’s very newest DSLR and from what I’ve heard, it is quite powerful! Unfortunately, being the newest, it is also very expensive…

    Also, you have to remember that your lens is old! According to Ken Rockwell, it was released in 1998!

    One more question, what focus mode do you use? It could possible make a difference if you use continuous vs. One shot, I’m not sure.

    Abigail Blackstone

    I made the folder public, so all of you should be able to see the pictures in the folder. I do understand that my lens was created a long time ago, but I have only had it for a year and a half. Even though it is old, it seems like Canon would have made a better product than that. The 7D Mk II is sort of expensive, but not more than I am willing to pay. I shoot in continuous on evaluative metering.

    Abigail Blackstone

    I think I was shooting one shot, which I don’t usually do, so that may have something to do with it. Usually I shoot Al Servo.


    Just a thought, do you shoot anything in low light? If you do, the 7D is a crop frame sensor, whereas a full frame would be really nice if you are going to spend a ton of money. Now, the cropped sensor does help with your zoom if that is all you do.


    Hi, I agree with all the others, that I’d more quickly fault a t3 than the lens, but I think it would be disappointing to upgrade the camera and realize that it was the lens after all.
    Here’s the problem: you say that it hasn’t always done this. That’s odd, for an afma problem. If the combo was working perfectly, and then lately you pull it out and it doesn’t it indicates that the state of your equipment has changed. It can happen that shutter boxes and mirror assemblies get messed up, but it would seem far more likely that the lens would get messed up. (much more complex, many more moving parts, etc)
    @jamesstaddon, I agree about being more willing to credit a t3 with a mistake than an L-lens, but in the case of the 100-400 I’m less sure. I researched this lens quite a bit in the last year and basically read that there is a lot of sample variation and a lot of them need afma. (60d doesn’t afma either though the 50d and the 70d do) Because of all the reviews I read about it, and for other reasons, we went with the 70-200 and 2xIII, though it was a rather more costly route.
    @thefarmhand. True about full-frame, but the options are tricky. The 6d and 5d II have basically the same autofocus system as a rebel. (11 and 9 autofocus points respectively with one cross-type in the middle) So your full frame options with a better focusing system are in the 1d series or the 5d mark iii and both options are somewhat more costly. If you’re not printing bigger than 8×12 the 1d iii is interesting I suppose.
    A new body might fix focusing errors. It would at least give you afma if that were indeed the issue. I might add that the 7d mark ii has apparently had some autofocus issues itself, and canon has been servicing a lot of units. In your shoes I’d be looking hard at a used 1d iv for it’s faster lens drive and autofocus-linked spot metering, if you’re in that price range. Otherwise I’d look at the 70d. A bit less and I’d look at the original 7d or the 1d iii, used.
    I personally would be afraid of buying a new camera and finding out that it was the lens after all. Do you have any other lenses that would give a shallow depth of field? Test them out and see if the autofocus accuracy is better, or the same. (don’t bother with testing third-party lenses, such as sigma tamron and the rest, autofocus accuracy is always a wash with non-proprietary lenses) If your other lenses perform perfectly, all fingers pointed at the 100-400 as the culprit. If they all perform similarly, your t3 is probably guilty.
    I would also send the combo through some testing: set up a high-contrast test target and your camera on a tripod. Also place something such as a ruler beside the target at an angle so you can see it and so that the ends will be closer to the camera and further from the camera than the target. Then focus the camera, then unfocus the lens manually, focus again, unfocus manually again, examining every picture. You can look at the ruler to see where it was focused compared to your target. You might start to see a pattern of off-focus.
    Technical notes:
    A back-focused or front-focused lens would actually account for the situation fairly well imo: A camera’s autofocus system is never 100% perfect. In fact, it is impossible to be “perfectly” perfect because, in theory the depth of field of perfect focus is actually infinitely thin. So the autofocus sends the lens to the “right” place within given tolerances. Lenses and cameras are also built to given tolerances. Supposing that the the tolerances are an arbitrary +/- 3 focus units, a camera of, say, +2 with a lens of -2 will seem perfect, even though neither lens nor camera is perfect. The same camera at +2 with a lens that is dead on at 0 will only seem so-so even though the lens is actually closer than the first. The same camera at +2 paired with a lens at +2 will seem actually pretty bad even though neither are really beyond tolerances. With an 18-55 kit lens, it would be impossible to detect these discrepancies, however with a longer lens, or a fast prime, such as the 85mm 1.2 the depth of field becomes so small that any errors are immediately apparent. Plus the buyer of a 2000$ lens is 10x more committed to having a perfect lens than the buyer of a 200$ kit lens.
    Now, autofocus systems being made by imperfect people are also imperfect, especially our phase-detection autofocus. (As a side note, if you were to always use your live view, contrast detection autofocus, your in-focus rate will almost certainly rise) Sometimes they miss. Now, if your camera-lens combo is, say +4, your autofocus will normally get it wrong. But, if your autofocus misses and arbitrarily lands on -4 the image will be tack-sharp. So what I’m saying is that, if this were the case, the times your pictures end up sharp would be your camera-lens combo actually getting it wrong.
    Read more on this by a person more knowledgable than me here:


    @nasa Would a good test be to find a friend with another camera to borrow, and try the lens on that? That’s probably what I would start with vs buying another camera to test with, and risking that not being the problem.


    @thefarmhand yup, exactly. That’s a good idea borrowing another camera, and a lens too. Mix up the combos and see if ya can’t find a culprit. I’d give that a try; probably simpler than setting up a laboratory test like I suggested.

    Ezra Morley

    Even though it is old, it seems like Canon would have made a better product than that.

    As a rule, Canon’s L lenses are the best you can get in every way, including longevity, etc. And I know there are still lots of people who use the original 100-400, so not all of them are worn out. But on the other hand, as @nasa said there is a lot of sample variation, so it’s possible that the lens you got has an issue of some sort that it’s not supposed to have.

    I did take a look at the pictures on Google Drive, and again, they all look pretty good to me! Of course, I’ve never owned an L lens, so I may not know what to look for in pictures taken with an L lens. Unfortunately, even those pictures were highly compressed, so it makes it very hard to judge “feather-splitting” sharpness.

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