What am I doing wrong? Is the lens back/front focusing?

sanjosedave

EOS RP
Jan 17, 2012
202
0
Canon 7DII with Canon 100-400mm II Tripod, ISO 640, 400mm, f5.6, 1/2000

Bird 1 pic shows the focus point

Bird 2 pic shows an out of focus bird based on the focus point in bird 1

What am I doing wrong?

Thanks
 

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neuroanatomist

I post too Much on Here!!
Jul 21, 2010
24,620
2,106
Can you try a simple test? Pick a static subject with some depth and good contrast (red wine in a glass on a dining table comes to mind, probably because that’s in front of me), shoot it with both regular AF and in live view, and compare the results.
 

Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
15,559
777
Can you try a simple test? Pick a static subject with some depth and good contrast (red wine in a glass on a dining table comes to mind, probably because that’s in front of me), shoot it with both regular AF and in live view, and compare the results.
Yes, test autofocus where you control all the variables. High contrast subject, lots of light, stable tripod, high shutter speed, for a 400mm shot, turn off IS and use 1/800 or faster shutter.

As Neuro said, compare live view and phase detect. Then, turn on the IS and take shots with both live and phase detect again, the results might point you in the right direction for further tests.

Dust on the AF sensor can play havoc with AF, there are many possibilities, but first do the basic tests to verify the problem.
 

Photorex

EOS RP
Nov 19, 2016
250
39
Canon 7DII with Canon 100-400mm II Tripod, ISO 640, 400mm, f5.6, 1/2000

Bird 1 pic shows the focus point

Bird 2 pic shows an out of focus bird based on the focus point in bird 1

What am I doing wrong?

Thanks
Did you turn off the IS on the lens?
This does not look like an AF issue to me. Rather an unsharpness caused by the IS.

Frank
 

Kit.

EOS 6D MK II
Apr 25, 2011
1,419
799
Look at the image of the reflection in the bird's eye. It doesn't look unsharp; it looks motion-blurred.
 

Kit.

EOS 6D MK II
Apr 25, 2011
1,419
799
I thought about that, but he said it was shot at 1/2000 of a second, said he was using a tripod and the bird is standing still.
It might be helpful to see the Exif of the original image. If we trust the provided data, it looks like an IS-related problem.
 
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Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
15,559
777
It might be helpful to see the Exif of the original image. If we trust the provided data, it looks like an IS-related problem.
Yes, 1/2000 with IS on can sometimes be a issue. A test with both IS off and on but similar settings might pin it down to the use of IS with a high shutter speed, or even a IS issue.
 

Graphic.Artifacts

EOS 7D MK II
Aug 1, 2017
467
271
My 7D mark II would drop a clunker like that every once in a while if I was shooting servo AF at 10 FPS. I always figured it was due to the mirror not getting settled between frames and the AF module getting a false read on the subject.
 

dcm

Good or bad - it's not the gear.
Apr 18, 2013
742
79
Another possibility. I noticed a couple of other things in the view, such as an object off to the left. You didn't describe the environment you are shooting in, but I've had the situation where another smaller object that was nearer passed through the AF point, causing AF to shift. By the time the shutter released it had moved, but the focus is set near which causes everything behind to be out of focus. I was fortunate to spot the in-focus fly off in the margin. With a really tight shot it may be out of frame. This depends on how you have your AF tuned.
 
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Photorex

EOS RP
Nov 19, 2016
250
39
Canon 7DII with Canon 100-400mm II Tripod, ISO 640, 400mm, f5.6, 1/2000

Bird 1 pic shows the focus point

Bird 2 pic shows an out of focus bird based on the focus point in bird 1

What am I doing wrong?

Thanks
could also be an effect of scintillation with different temperated layers of air between the object and your lens. E.G. when you are shooting from a warm interior into a colder ambient.
 
Last edited:
Oct 4, 2019
2
1
I don't know if it's the same, but I have experienced something similar on my 70D and 5DIV. I think 5DIII worked correctly, but it's possible that I didn't put it into same conditions. Lenses: 85/1.8, then later 135/2L.

When lighting is a bit lower, for example in a shade an hour before sunset, and when trying to capture an animal with fur, for example a gray cat (target being its head), camera may front-focus by a lot. No seeking, quick lock, but completely off. There wouldn't be anything near used focus points that is in focus. This post sounds a lot like it. I found one post mentioning issues with furry animals, but that's it.

I just took this as a Canon AF limitation, initially thinking it is due to a lower level body and older lenses. Never had success reproducing this in a controlled environment. Maybe I should buy a cat, or at least a plushie...
 

Valvebounce

EOS 5D SR
Apr 3, 2013
4,269
215
52
Isle of Wight
Hi SecureGSM.
I’m not sure what it was supposed to explain, but as a 7DII + 100-400 user I thought I would read it, the whole thread is built on the mistake that the picture was taken with a 7DII, it was not, it was taken with a 1Dx (for which Art Morris apologises!).
Art then goes on to say that camera / lens shake is a factor of the square of the focal length, my interpretation of this (Art doesn’t clarify his statement) is that rather than a shutter speed of 1/focal length he believes that we should use 1/focal length ^2 (squared)!
For the effective focal length of 896mm that he gives, this would require a shutter speed of 1/802,816th of a second! I suspect that Art is not an idiot, just that he does not understand the concept of squared, however it leaves me with little confidence in his post.
It also leaves me with the suspicion that he may have been confusing the recent hypothesis that a value of 1/2x focal length is required to prevent camera shake on higher density sensors including the 7DII.

Cheers, Graham.

i suggest reading in its entirety including comments. I hope it explains.

 

YuengLinger

EOS 5D MK IV
Dec 20, 2012
2,649
772
Southeastern USA
Hi SecureGSM.
I’m not sure what it was supposed to explain, but as a 7DII + 100-400 user I thought I would read it, the whole thread is built on the mistake that the picture was taken with a 7DII, it was not, it was taken with a 1Dx (for which Art Morris apologises!).
Art then goes on to say that camera / lens shake is a factor of the square of the focal length, my interpretation of this (Art doesn’t clarify his statement) is that rather than a shutter speed of 1/focal length he believes that we should use 1/focal length ^2 (squared)!
For the effective focal length of 896mm that he gives, this would require a shutter speed of 1/802,816th of a second! I suspect that Art is not an idiot, just that he does not understand the concept of squared, however it leaves me with little confidence in his post.
It also leaves me with the suspicion that he may have been confusing the recent hypothesis that a value of 1/2x focal length is required to prevent camera shake on higher density sensors including the 7DII.

Cheers, Graham.
Good catch. I think he simply meant double the focal length, just guessing. Not a defense, but from what I understand, he was often sleep deprived when writing blog entries at that time in 2015. Like two hours a night for days or weeks at a time. Also wonder why he never fixed the error.
 

AlanF

Canon 5DSR II
Aug 16, 2012
5,830
3,363
Good catch. I think he simply meant double the focal length, just guessing. Not a defense, but from what I understand, he was often sleep deprived when writing blog entries at that time in 2015. Like two hours a night for days or weeks at a time. Also wonder why he never fixed the error.
The idea behind it is that the amount of shake goes up faster than the focal length, possibly as the focal length squared, for the very long focal lengths, but it doesn't start at zero. The way this translates into practice is that say the shutter speed necessary at 400mm is 1/400s, then at 800mm it is 1/(4x400)s not 1/(2x200)s. Frankly, 1/400s is not good enough for a 400mm lens with IS on a high density sensor when you start serious cropping.
 
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YuengLinger

EOS 5D MK IV
Dec 20, 2012
2,649
772
Southeastern USA
The idea behind it is that the amount of shake goes up faster than the focal length, possibly as the focal length squared, for the very long focal lengths, but it doesn't start at zero. The way this translates into practice is that say the shutter speed necessary at 400mm is 1/400s, then at 800mm it is 1/(4x400)s not 1/(2x200)s. Frankly, 1/400s is not good enough for a 400mm lens with IS on a high density sensor when you start serious cropping.
That makes more sense!
 

stevelee

FT-QL
Jul 6, 2017
1,262
290
Davidson, NC
With the 100-400L II, I recently shot the moon and Jupiter. With IS on at 400mm, handheld shots I took at 1/320 second looked good enough to post one of them, as I did in the moon section. I cropped it and posted a 100% pixel peep. I didn’t add any extra sharpening, and just did a bit of highlight recovery in ACR. My camera won‘t shoot at 1/160,000 second anyway.