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FORUMS Canon Cameras, Lenses & Accessories Canon EOS Digital Cameras 
Thread started 06 Jul 2010 (Tuesday) 02:10
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Focus confirmation when shot is not in focus

 
Snydremark
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Jul 06, 2010 02:10 |  #1

Lately I've been running into an issue where the camera "thinks" that a shot is in focus even though it isn't.

Body is a 40D and the lens I'm seeing the problem with is a 100-400L. What will happen is that the focus point in the viewfinder will flash red as if the shot is focused and AF will stop; but the image will be no where even CLOSE to actually focused. When this happens, I have to hit the AF button one or two more times to get the lens to continue trying to focus and bring the image into true focus.

So, my question is whether the body or the lens, or some combination of both determines whether an AF shot is actually focused.

Thanks in advance!


- Eric S.: My Birds/Wildlife (external link) (R5, RF 800 f/11, Canon 16-35 F/4 MkII, Canon 24-105L f/4 IS, Canon 70-200L f/2.8 IS MkII, Canon 100-400L f/4.5-5.6 IS I/II)
"The easiest way to improve your photos is to adjust the loose nut between the shutter release and the ground."

  
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EdWood
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Jul 06, 2010 02:43 |  #2

Doe this happen with any other lens? If not, it is the lens.




  
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philwillmedia
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Jul 06, 2010 03:13 |  #3

It sounds like you're in "one shot" or "AF focus" and you are slightly moving between when the focus locks and when you actually taking the shot.


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Snydremark
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Jul 06, 2010 09:58 |  #4

EdWood wrote in post #10484418 (external link)
Doe this happen with any other lens? If not, it is the lens.

I've only seen it happening with that lens :( That's what I was afraid of, but I wanted to see if anyone else had heard of this happening

philwillmedia wrote in post #10484497 (external link)
It sounds like you're in "one shot" or "AF focus" and you are slightly moving between when the focus locks and when you actually taking the shot.

Except that there is never a point in this process where it is in focus TO lock. Imagine you're shooting at a subject 6 feet away, then switch to trying to focus on a subject 30ft away but the lens stops and "locks" focus at a distance of 15 feet, even though there isn't anything at that distance to get in the way.

It IS mostly in One Shot, although I've had the focus give up using AI Servo, too. I've had the lens for 9 months, but I've only had this issue for about 3 to 4 weeks.


- Eric S.: My Birds/Wildlife (external link) (R5, RF 800 f/11, Canon 16-35 F/4 MkII, Canon 24-105L f/4 IS, Canon 70-200L f/2.8 IS MkII, Canon 100-400L f/4.5-5.6 IS I/II)
"The easiest way to improve your photos is to adjust the loose nut between the shutter release and the ground."

  
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hpulley
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Jul 06, 2010 10:17 |  #5

What is the focus distance limiter set to, 1.8m or the farther distance? Are you in focusing distance?

What setting do you have for Custom Function C.Fn III-1 Lens drive when AF impossible? My 100-400L works fine on my 40D. I enable focus search (setting 0 for C.Fn III-1) so it keeps searching even if it misses lock the first time through the focus range.

Is it actually in focus or not? Is the little green focus confirm light at the bottom solid or flashing? Will it take a shot in ONE SHOT mode like this? If it has a solid green confirmation light and ONE SHOT will take a picture out of focus like that then the lens or body are messed up; if only this lens does it then it might need a trip in though if you have backup equipment it might be safest to send body and lens in. Before sending it in, have you tried cleaning the lens contacts?


flickr (external link) 1DIIN 40D 1NRS 650 1.4xII EF12II Pel8 50f1.8I 28-80II 17-40L 24-70L 100-400L 177A 199A OC-E3 RS-80N3

  
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Snydremark
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Jul 06, 2010 10:41 |  #6

hpulley wrote in post #10485843 (external link)
What is the focus distance limiter set to, 1.8m or the farther distance? Are you in focusing distance?

What setting do you have for Custom Function C.Fn III-1 Lens drive when AF impossible? My 100-400L works fine on my 40D. I enable focus search (setting 0 for C.Fn III-1) so it keeps searching even if it misses lock the first time through the focus range.

Is it actually in focus or not? Is the little green focus confirm light at the bottom solid or flashing? Will it take a shot in ONE SHOT mode like this? If it has a solid green confirmation light and ONE SHOT will take a picture out of focus like that then the lens or body are messed up; if only this lens does it then it might need a trip in though if you have backup equipment it might be safest to send body and lens in. Before sending it in, have you tried cleaning the lens contacts?

Focus limiter is set to 1.8m and focus distance is between 20m to Infinity

C.Fn III-1 is set to Enable search; the behavior you describe is how the lens has previously functioned, up until around a month ago.

Not in focus, but the confirmation light is solid. I haven't actually pushed the button at that point to see if it would snap a shot off or not, since I see that it's not focused yet.

I'm going to try an eraser on the contacts and see if that clears it up; but yes, if I have to send it in I'm just going to send both the lens and body in. I picked up a 7D yesterday and have some other lenses to work with until that one comes back. It's just unfortunate because 90% of my shooting is done with the 100-400. I'll just have to get better with the 70-200 or 100mm macro if I have to send things in :p


- Eric S.: My Birds/Wildlife (external link) (R5, RF 800 f/11, Canon 16-35 F/4 MkII, Canon 24-105L f/4 IS, Canon 70-200L f/2.8 IS MkII, Canon 100-400L f/4.5-5.6 IS I/II)
"The easiest way to improve your photos is to adjust the loose nut between the shutter release and the ground."

  
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hpulley
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Jul 06, 2010 10:49 |  #7

Snydremark wrote in post #10485989 (external link)
...
I'm going to try an eraser on the contacts and see if that clears it up; but yes, if I have to send it in I'm just going to send both the lens and body in. I picked up a 7D yesterday and have some other lenses to work with until that one comes back. It's just unfortunate because 90% of my shooting is done with the 100-400. I'll just have to get better with the 70-200 or 100mm macro if I have to send things in :p

It is my favorite lens as well! So far so good on mine. Hopefully the eraser trick does it, otherwise I hope it is under warranty as I hear it is $300 just to open up and clean that lens.

Perhaps this is an opportunity to get a teleconverter to pair up with the 70-200 f/2.8?


flickr (external link) 1DIIN 40D 1NRS 650 1.4xII EF12II Pel8 50f1.8I 28-80II 17-40L 24-70L 100-400L 177A 199A OC-E3 RS-80N3

  
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Snydremark
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my very own Lightrules moment
19,538 posts
Gallery: 63 photos
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Location: Issaquah, WA USA
     
Jul 06, 2010 15:11 |  #8

hpulley wrote in post #10486064 (external link)
It is my favorite lens as well! So far so good on mine. Hopefully the eraser trick does it, otherwise I hope it is under warranty as I hear it is $300 just to open up and clean that lens.

Perhaps this is an opportunity to get a teleconverter to pair up with the 70-200 f/2.8?

Still under warranty, so if it goes back it's not the end of the world; just a bummer to be without it :)

Yeah, the TC thought occurred yesterday too. I just couldn't justify tacking that on to the 7D purchase without troubleshooting the 1-4 a bit further ;)


- Eric S.: My Birds/Wildlife (external link) (R5, RF 800 f/11, Canon 16-35 F/4 MkII, Canon 24-105L f/4 IS, Canon 70-200L f/2.8 IS MkII, Canon 100-400L f/4.5-5.6 IS I/II)
"The easiest way to improve your photos is to adjust the loose nut between the shutter release and the ground."

  
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Focus confirmation when shot is not in focus
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