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Problem with 400mm L 5.6 clarity


On image tests my 400mm L 5.6 is performing significantly less sharp than my new 100-400mm lense. The only think I can think of that would have damaged the 400 was condensaton in the body from temperature changes. Shots are all tribod and cable triggered. No filters on either lens. This is of course cropped way in. Any ideas? The 400 is about 9 months old. Can it be cleaned internally?



7D, EFS 18-55 IS, 400mm L 5.6f, 100-400mm L


The top photo looks OOF so if it is there is no way to tell if the lens is "sharp" or not. Maybe you were too close?

EOS 1DX and 1D Mk IV and several lenses!

View solution in original post


It is possible the lens' focus is out of calibration. Focus mechanisms can wear with use or just get out of adjustment with a bump or even be mis-adjusted from new. This can be adjusted and corrected, worn or faulty parts can be replaced if needed.


IMO it's unlikely that the lens needs cleaning inside. Usually stuff inside a lens - even a lot - doesn't effect focus and sharpness very much... It causes flare, veiling, loss of contrast and reduced color saturation.  If images showed uneven sharpness, that might indicate a decentered lens element or group, another problem that often can be corrected. But just judging from your sample images, there don't appear to be problems of those types. I doubt you'll find anything of significance, but you can inspect the inside of a lens with a flashlight. Just don't panic if you see some specks of dust here and there. Those are common and not a problem unless there's a lot... a whole lot!


You probably should just send the lens in and have it checked and calibrated.  


However, there are other things you can look for first, to rule out as possibilites...


1. As already suggested, that lens' closest focusing distance is about 3.5 meters (11.5 feet). If closer than that, you won't be able to focus So, yes, be sure you simply aren't trying to focus too close.  (Notes: For comparison, your 100-400mm's closest focusing distance is 1.8 meters/5.9 feet. Also, adding a macro extension tube will allow the lens to focus closer).


2. Do you have a filter on the lens? If so, try without it. Quality filters can be helpful in some situations, but cheaper ones can make a mess of images and some lenses simply don't work well with the filters (actually your 100-400mm is one that is pretty widely known to not work well with filters... even good ones).


3. You mention using a tripod and remote release, and those are good for tests like these. Are you also locking up the mirror? At certain longer shutter speeds (usually between roughly 1/30 and 1 second) mirror slap can sometimes cause enough vibration to give some camera shake blur in images. The 100-400's Image Stabilization should be able to correct for that. But the 400/5.6L doesn't have IS, so would be more prone to show any vibration effects. When using really long telephotos without IS, at times I've put a beanbag on top of the camera and lens to help prevent vibrations, too.


You didn't mention what camera you are using, but an APS-C 1.6X crop model is more susceptible to camera shake, than a full frame model would be. On the other hand, the larger mirrors in full frame models are more likely to give mirror slap effects (all have some dampening, I'm sure.... but it likely varies with different models) .  


Also, Canon has published a white paper about the 18MP APS-C cameras being particularly susceptible to any form of vibration... They recommend using slightly higher shutter speeds to offset this, especially with the crop cameras with very dense sensors.


4.  Hopefully you are using One Shot focus for those test shots. Be sure to restrict to only the center AF point. And  If your camera has it, try using Live View. That employs a completely different method of focusing and is a good way to test the camera and lens.


5. Use a clean rag lightly dampened with a few drops of isopropyl (rubbing) alcohol to clean the electronic contacts on the back of the lens. Perhaps some oils or dirt on the contacts are interrupting communication between the camera and lens, effecting focus.


Those are things you can try yourself at no cost. Since the lens is less than a year old, it should still be under warranty, so I wouldn't hesitate to send it in to Canon for calibration, if none of the above helps.


Alan Myers

San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories






View solution in original post


@ebiggs1 wrote:

Bob fome Boston said,

"Advising an experienced photographer not to try it, ..."


But I don't know this? Experienced?  Taking it for granted are we?  Smiley Frustrated


The thread has been going for more than 17 months, so it's a bit hard to keep track of the players. But I don't see lack of experience as a significant problem with any of them.


"You take a series of pictures and see which one looks the sharpest at the operative AF points."


Now, Bob from Boston, we both know that is not how to do it.  Don't we?  It takes as Alan Myers suggested concentrated work done on a tripod. At a given target and range, carefully.  Same, same each time.


Maybe so, if you think you have to be absolutely certain of your choice between 0 and +1 or between +8 and +9, etc. But I assure you that you don't need a printed target or a tripod to see the difference between 0 and +9. So yes, unless you're a compulsive pixel peeper, that's exactly how to do it. There have been some good papers written on how to do it intelligently, like photographing a scene with objects at various depths, so that you can see them come in and out of focus. But that's just an implementation detail.


It is a moot point because that isn't the OP's problem.


I don't see how you know that, given the evidence presented.


Philadelphia, Pennsylvania USA

I was viewing at 100% on a 55" 4k panel

The oisser has horrid color and nasty compression artifacts but is sharper. Ie i dont think the oisser is better i think something is wrong or mis configured on my end with the 100-400

I was assuming an L lens would give superb compare dto the junk i have. When i stop down. It does. Incredibly sharp in my opinion. I dont compare to 300 or 400 primes because i dont have those. I compare to my crappy 75-300 and my old 100-300L.

I see someone made a new thread i will jump their. I apologize for hijacking this thread i am on my mobile and did a search for 100-400 focus issues and this thread cane up. My bad 🙂

I tried all 41 mfa positions. None help and seem only to make it worse or no change. I reset it back to zero.

Exif should be on. Does imgur strip it? The images are untouched uploaded direct from the memory cards.

Does the 5dmark ii let you turn off exif? Where is thisnsetting if yes? I will check imgur uploads when i get home tonight.

I always set cams to center point focus and one shot. Cant really use anything with what i shoot (500mph little missiles)

Odd you consider the B29 to be a tough or fast subject. I consider it to be a crazy easy and enjoyably snail like subject. I can take my time and pick my shots at leisure it is so slow and majestic. I guess that is just in comparison to what i typically shoot.

You can see some of what i do at and

Most of those are xti with cheap 75-300 or casio exf1 the bigger stuff i used the xti for its superior iq for the scooters of course i use the f1.

I do not think i am puxel peeping. You would have to tell me what that is. I am simply comparing iq to images i have been capturing for 20 years with my far inferior cams and glass.

In many of these shots i can physically see in the viewfinder that it simply is not in focus.

I will work on some 32ft test shots on a tripod.

I dont expect miracles. But i do expect this $1500 lens on a $2000 body to give better results than my $400 xti and $50 75-300 and in more than just noise and raw pixels.

When i get a shot in focus i am quite impressed. Just seems to have trouble getting in focus. Again up close seems fine. Its when you get past 20ft that seems to be the problem. Past 300ft the problem is slightly less but still present (ala the B29 which should be a lot sharper for such a clean easy target)

ebiggs1 wrote: 



This one I advise against doing at this juncture.  Without knowing you better, you could make everything a lot worse.  It might be good, however, to make sure it is set to zero, no adjustment...

I see your point....


Maybe Micro Focus Adjusment should just be considered as a final resort after careful testing, before sending the lens off for service and calibration or repair.


Since MFA is a feature on 5DII someone wanting tto get that last little bit of focus accuracy out of a lens might want to learn to use it. Some folks find it makes the difference between ""My focus is a wee bit soft" and "WOW!"


But you are probably right... For initial testing, it would be good to just check that MFA is zeroed out. Then, if tests show some relatively modest amount of calibration is needed, learn to use MFA and see if that can correct it. If a lot of adjustment is necessary or if MFA is only able to correct it partially, the lens still may need to be sent in for service and calibration. Even after that work is done, it's possible that MFA will still be needed to fine tune it for that particular camera.


It definitely is not a good idea to just try every MFA setting and see what happens. That's just down to luck, that you'll find a setting that helps. You need to use a much careful and planned approach, and with a zoom such as the 100-400mm, I would run the exact same test at 100, 200, 300 and 400mm settings... come up with an average adjustment and set it... then rerun the tests at those focal lengths to confirm it's working consistently. (Using a software such as FoCal does more automatically.)


nerys wrote:
...what do you mean my exit date is missing I upload raw to imgur does imgur remove EXIF data?


EXIF data, sometimes referred to as metadata, is information stored within a digital image file, including all the settings that were used on the camera, lens & camera serial numbers, copyright info, and much more. I have never heard of "imgur" or uploading a RAW file. I mostly shoot RAW, but I process and convert to JPEG, saving them with EXIF intact, to upload online.


No, there is no way to "turn off" EXIF in 5DIII (or any other camera, for that matter). All digitals cameras record some sort of basic information, embedded in the image file. It really only takes up a little space... but with many softwares "save for the web" strips it off, probably to save that little bit of space.


nerys wrote:
I was viewing at 100% on a 55" 4k panel...


OMG... viewing on that large a screen at 100%, no wonder you're thinking the lenses aren't sharp. That's pretty extreme, though you can work to optimize the quality from the lens and camera. Depending upon how close you are to that screen, you are probably "pixel peeping" Smiley Happy, which is just looking at images way too large and way too criticall.


What do you do with your images? Put them online or make prints or something else? Or do you just view them on that gigantic HD screen?


Didn't know to ask before what post-processing you are doing... Since you are shooting RAW, the images will need some work, including as a final step some sharpening. If those RAWs have not been post-processed, it's apples and oranges to compare with JPEGs from your point-n-shoot camera, which should be fully processed and probably even sharpened.


nerys wrote:
...I always set cams to center point focus and one shot. Cant really use anything with what i shoot (500mph little missiles)

Odd you consider the B29 to be a tough or fast subject. I consider it to be a crazy easy and enjoyably snail like subject. I can take my time and pick my shots at leisure it is so slow and majestic. I guess that is just in comparison to what i typically shoot....


Now we're getting somewhere! (If we'd been able to see the EXIF of the sample images, we might have caught this earlier.)


Center focus point... good (especially on 5DII... all the other AF points aren't nearly as good for moving subjects).


One Shot.... bad! This is very likely a big part of your problem, at least with moving subjects. One Shot is great for stationary subjects and the setting you should use shooting targets for lens tests. But it generally cannot be used for moving subjects.


The way One Shot works is that the lens focus starts and runs until the sensor in the camera detects it's in focus, then focus stops, locks and you get Focus Confirmation (green LED in the viewfinder lights up and, if you have it enabled, there's an audible "beep"). But, if subject is moving  it can quickly move out of focus...


The longer the focal length, the larger the aperture and the closer the subject, the shallower depth of field will be... and thus the worse that the focus error is likely to be, trying to use One Shot for moving subjects.


You should be using AI Servo for moving subjects. That is continuous focus mode and is designed to work with moving subjects. It will keep running and updating focus as long as you maintain half-press on the shutter release button (or keep the back button pressed, if using Back Button Focusing technique).


To track moving subjects, definitely stick with the center AF point on 5DII. The other visible AF points in this camera model are typically not up to the task. I have and use a 5DII myself... but not for action/sports shooting. It's a great camera for portraits, landscape, architecture, etc.... but for sports/action I mostly use a pair of 7Ds because they have much faster and more responsive AF that's great for moving subjects. With them I only miss focus occasionally... probably 2 to 4% of all my images... and I bet about half of those are my fault, not the camera's.


You have to work to keep the AF point right on the subject, too.


The 5DII does have a Focus Assist setting (one of the custom functions, I believe).... that might help. This only works in AI Servo/moving subject mode.  The camera actually has 6 more "hidden" AF points that aren't shown in the viewfinder. They are clustered close around the center one. In fact, when this is enabled, the circle in the center that indicates Spot Metered area becomes like one big AF point. This works best with subjects against a plain background that is unlikely to distract the AF and cause focus errors. I don't use this feature on my 5DII, perhaps largely because it's not my camera of choice for action shooting.



Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories



Ahh forgot to add. No filters. I dont typically like them

I just got religious using the elns cover for protection.

Yep already did it all 41 settings no change or worse. So if it is a focus issues it is outside the mfa compensation range. Reset to zero.

I ahoot rockets. I can not use ai modes as they invariably ie 99% of the time get borked by the background sky versus the rocket.

My sop is to focus on a geound object at equal distance to rocket and lock focus in place for the eventual lift off shot.

When i toom several shots of the b29 i would reaquire focus lock between each rapid shot to allow the system to compensate for distance changes (thiugh minor) the b29 was a rather large target consuming 10% of the frame or more so should be no problem for the af system.

My rockets many times are 2 to 5 % of the frame hence why i need more mm and more pixels.

To end up with more usable pixels after the crop.

I know what exif data is but you said their was none. Since i did not remove something must have.

Raw in this context did not mean raw file format but raw as in naked ie untouched. No resize or filtering the straight jpg off the memory card. Zero post processing. You see the file as it came out of the camera.

Remeber my subjects are doing 200 to 1200 mph. No ai system i can afford will work on that. 🙂

One shot is not the problem. I am shooting stationary large unmoving objects at 300mm and the 100-300 exhibits none of these issues. Its images are as sharp as i expected them to be.

My other pictures look fine on my screen. I have no reason to zoom in and examjne pixels. As long as it looks good on an 8x10 or 11x16 print i am happy. Got lucky been using tube crt's until this past winter simply because 1080p is a huge downgrade for me (2048x1536)

Now i view at 3840x2160. Nice. Scored open box for $800 cyber monday. It is my computer monitor. I dont really watch tv.

"I ahoot rockets."


But the samples are not 'rockets'.  So I see this as a none issue.


" I am shooting stationary large unmoving objects at 300mm and the 100-300 exhibits none of these issues. Its images are as sharp as i expected them to be."


This is what does not make sense.  It does suggest the lens needs to be checked by Canon.  One works.  The other doesn't.  What other conclusion can you draw?

Do the testing Alan Myers and I suggest.  You will not know until either Canon does it or you do.  But one or the other.

EOS 1DX and 1D Mk IV and several lenses!

"I was viewing at 100% on a 55" 4k panel"


Also has nothing to do with what you have shown here.  Does it?

EOS 1DX and 1D Mk IV and several lenses!

Yes, I looked at your website and see what you are photographing...


@nerys wrote:
Iahoot rockets. I can not useai modes as they invariablyie 99% of the time getborked by the background sky versus the rocket....

... and I fully agree that AI Servo will not work for that. They are just moving too quickly and you are too close (it would be different if you were photographing a launch at Cape Canaveral and standing one or two miles away with a big lens... and that big rocket is accelerating to 17,000 MPH).


With a subject like your model rockets, YES... you need to pre-focus the subject as you are doing, then trip the shutter at the moment of launch. One Shot is one way to do that. (Manual focus would work, too... Or AI Servo in combination with Back Button Focusing).  


However, your method with the B29 should be AI Servo. The technique you are using with One Shot... I've heard it called "bump focus"... simply works very poorly. It guarantees that a large number of your images will be mis-focused. I teach a lot of sports shooting seminars and have seen people using this method a lot. Invariably, they are stunned at how much more capable their camera is capturing moving subjects with AI Servo... I'm talking about "sports speeds" such as the airplane flying by at some distance, cars racing past, horses going over a jump, cyclists riding by, basketball players dunning down a court, etc..... Not "rocket speeds" up close... but general movement and in most cases from a distance. Even airplanes or cars doing 200 MPH and faster (so long as you aren't standing right next to them)....  


Porsches in Turn 1, Mazda/Laguna Seca Raceway

... Above is one of about 1200 shots I took at a vintage race a few years ago, using the AI Servo technique I'm telling you about. I would estimate I missed focus on no more than 10 or 20 shots... and most of those were likely my fault, not the fault of the 50D cameras I was using.


Using One Shot for moving subjects is almost certain to cause missed focus issues. Unless the subject maintains the exact same distance while moving past you, focus will be off because the subject has moved out of focus before you can trip the shutter. And the longer the lens focal length, larger the lens aperture, closer the subject all make for shallower depth of field, which exacerbates the problem and calls for even more precise focus.


Using AI Servo and a single AF point that you work to keep that right on the moving subject - right where you want the camera to focus -  is how you keep the focus tracking the subject and avoid it being distracted by the background. Doing this I sometimes shoot a split second burst and get four or five or more in-focus shots in a row...

 Jumper 1

Jumper 3

Jumper 4


























The above series is a bit small here on the Internet, so you'll have to take my word that thanks to using AI Servo all three are in focus (actually there were more shots in this series... these are just the ones I show for composition and subject pose...all were in focus, none were out-takes for focus issues).


If I'd used One Shot and pre-focused on the jump, I might have been able to perfectly time a single shot... or I might have missed it if I didn't press the shutter release at exactly the right moment. But, by instead using AI Servo I got a series of shots, all in focus, including the three "keepers" shown.


Now, you generally shouldn't use AI Servo for "focus and recompose" technique (which is effectively what you're doing when you pre-focus for those model rocket launches), without also using another technique. That additional technique is called Back Button Focusing and it's very popular with sports shooters in particular, because it allows them to use AI Servo by default, even for focus-and-recompose. BBF separates AF control from the shutter release button and uses only one of the buttons on the back of the camera, under your thumb, to start and stop AF. More info about BBF can be found here in and article at the Canon Learning Center.

I gotta say, your and my 5D Mark II cameras really aren't the ideal sports/action/AI Servo models. The AF system of these isn't nearly as good tracking movement as some other models (such as my 7Ds).


But even the 5D II is capable of catching moving subjects at times, such as the redtail hawk at right. Actually I missed focus on a lot of shots of that bird, it was so fast, came so close and the 5DII just isn't fast enough.... But the bird was very cooperative, ignoring me and hunting right by me for nearly an hour of shooting. Redtail hawk flyby I'd probably get better with 5DII shooting moving subjects if I used it more often for that purpose more often... but to "put more pixels on target" with handholdable lenses, I prefer a crop sensor camera anyway.


Finally, don't confuse AI Servo with AI Focus. I never use AI Focus... It's an automated mode where the camera is supposed to detect whether or not the subject is moving, then switch to using either One Shot or AI Servo, as it deems appropriate. Problem is, there is a slight delay while the camera is making up its mind... and sometimes it chooses wrong.


So I make my own selection: One Shot or AI Servo. And because I also use BBF, I use AI Servo by default, only switch to One Shot in certain circumstances.


I am pretty certain some of your problems are that you're using the wrong focus mode... If you were in One Shot at that airshow, shooting the B29, that almost guaranteed missed focus. Switch to AI Servo and learn to use it, and it can almost guarantee in-focus shots instead!


You might really find more useful info about the Canon AF system in three half-hour videos, starting with this one.


There still might be some issues with focus with your lens and/or camera... service or calibration might be needed... or proper Micro Focus Adjustment may help. But I think if you change some of the techniques you're using in some situations you'll get noticeably better results.



Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7D(x2), 50D(x3), some other cameras, various lenses & accessories


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