# Something odd is going on with my Canon EF 17-40 F/4 L.



## pulseimages (Apr 28, 2015)

I've noticed this only a couple of times within the last couple of weeks during long exposures at night and usually at 17mm. It doesn't happen every time I photograph at 17mm just sometimes and I can see it on Live View. As soon as I zoom in the dark lines on the sides go away but the blueish stuff on the bottom are new. Has anyone seen this before? What's causing it? Thanks! I shoot with a Canon 6D when I use this lens.


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## Maximilian (Apr 28, 2015)

pulseimages said:


> I've noticed this only a couple of times within the last couple of weeks during long exposures at night and usually at 17mm. It doesn't happen every time I photograph at 17mm just sometimes and I can see it on Live View. As soon as I zoom in the dark lines on the sides go away but the blueish stuff on the bottom are new. Has anyone seen this before? What's causing it? Thanks! I shoot with a Canon 6D when I use this lens.


Hi pulseimages!

Looks really strange. Now ypu must find out if this is comming from the lens or the body.
Maybe you could try the following to answer some questions:
- Can you lend other lenses or FF bodies to cross check the issue?
- What were the exact shoting conditions when you could recognize it? 
Tripod? Aperture? Exposure times? Much light sources (relative to dark environment)? Light into the lens?
- Did you use lens hood or filters? If yes what brand/model/thickness?
- Did you use different memory cards?

I think about four reasons:
- Vignetting or reflection comming from the internal of the lens or from hood or filters (avoidable, no damage)
- something wrong with the optics inside the lens (send it to Canon for repair)
- something wrong with the mirror box or other mechanical parts in body (send it to Canon for repair)
- something wrong with the sensor or electronics in body (send it to Canon for repair)

If you can get more detailed, maybe I can also do some tests (having the 17-40 and FF body, but no 6D)


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## NorbR (Apr 28, 2015)

Looks like you can see the inside of your lens hood. Not good. 

First confirm that it's the case by taking the hood off, the problem should disappear. 
Then mount it back, carefully, making sure that it clicks in place like it's supposed to. If the problem goes away, then it was just a matter of the hood being improperly mounted in the first place. Happens. 

If the vignetting is still here, then time for a hood inspection. First make sure you're using the right one for your lens. If you're using a 3rd-party hood, or if you suspect that your hood may be damaged in any way, it may be time for a replacement. 

If the problem remains after all that, then your lens may indeed have a more serious problem ...


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## bitm2007 (Apr 28, 2015)

Check that your using the correct hood. I got something simular, when using the hood for the 24-105mm L on the 17-40mm L.


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## matukas (Apr 28, 2015)

Seems like a lens hood issue. If original, then not probably correctly seated.
I have never had hood (original) issues with mine on FF or crop body.
Look here:
http://www.the-digital-picture.com/Reviews/Canon-EF-17-40mm-f-4.0-L-USM-Lens-Review.aspx
Maybe you have hood 90-degree wrongly seated?
http://static.borrowlenses.com/images/store/LG17402.jpg


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## AcutancePhotography (Apr 28, 2015)

The OP stating that the black lines appear when the lens is zoomed in, seems to indicate that it is not the lens hood. One would hope that the OP checked the lens hood before posting. ;D

The blue stuff at the bottom, I wonder if that could be a fungus? I hope not.

But in any case, it has already been suggested that the OP needs to try this lens on a different body to see if it can be replicated. If it can't be replicated, the problem is in the camera.

Good luck with this. It could be an expensive problem.


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## neuroanatomist (Apr 28, 2015)

AcutancePhotography said:


> The OP stating that the black lines appear when the lens is zoomed in, seems to indicate that it is not the lens hood. One would hope that the OP checked the lens hood before posting.



Actually, he stated that the black lines are seen at 17mm and disappear when zooming in. So that's consistent with the hood as the cause. 

He doesn't really say about the blue at the bottom, but those 'bumps' look symmetrical and the curve of them blends into the black which also points to the hood.


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## AcutancePhotography (Apr 28, 2015)

Ah I misread that.


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## neuroanatomist (Apr 28, 2015)

I hope it is the hood, as that's an easy fix. The alternatives...not so much.


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## Marsu42 (Apr 28, 2015)

neuroanatomist said:


> I hope it is the hood, as that's an easy fix.



+1 for this theory esp. due to the odd two bumps on the bottom that are missing on the top - looks like a severely mis-aligned original hood or a 3rd party hood that isn't made for that lens at all (but maybe for the 17-40L on crop).


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## Matthew Saville (Apr 29, 2015)

This could also be an issue that is internal, or at the rear of the lens. Some Canon lenses have rectangular openings at the rear of the lens, and if you bump your lenses into your rear caps a lot I suppose you could bent / break something back there. Also, shine a flashlight through the lens to make sure nothing else internal has slipped around. The fact that this comes and goes when stopping down could mean something bad has happened internally.

Or, it could just be a 24-105 hood on a 17-40, LOL. ;-)


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## geekpower (Apr 29, 2015)

i don't know if it's even possible, but it almost looks like the hood is turned 45 degrees...


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## pulseimages (May 6, 2015)

You guys were right, it was the lens shade. Somehow the lens shade from my 24-105 L got swapped with the one for the 17-40 L and vice-versus. They do look similar though.


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## Maximilian (May 6, 2015)

pulseimages said:


> You guys were right, it was the lens shade. Somehow the lens shade from my 24-105 L got swapped with the one for the 17-40 L and vice-versus. They do look similar though.


Thank you for letting us know. Also thank you for beeing so honest 
I'm happy to see that there is no real problem with the lens. 
Enjoy taking pictures without needless vignetting


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