Why does my Canon 18-135mm lens make the viewfinder image jump when I manually focus?

Asked 2/12/2014

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When using my Canon 18-135mm IS lens, the image in the viewfinder shifts or tilts slightly at a certain point while turning the focus ring in manual focus. It seems to happen around the middle of the zoom range. I see it with image stabilization on or off, and I have only noticed it in manual focus. Looking straight upward seems to reduce or eliminate the issue. What would cause this kind of image jump?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

12y ago

2 Answers

1

Can you find the exact point where this happens? More properly: is there

  1. a point when it happens or
  2. is there hysteresis?

1: if you find this point, small back and forth movement of the focus ring makes big repeated jumps (do not play with this too much though ;-) )

2: you focus in one direction, then it jumps, but you have to go backward with focus considerably before it jumps back.

Because:

  1. means that the lens element path is somehow weakened or broken or has some play or dirt or some kind of a friction (there are several types of greases being used in a lens to properly achieve the required friction);

  2. usually means that a lens element has some play inside the lens holder ring - God knows its proper English name... It is two rings glued together on each side of the lens element, holding the lens element usually steady. So when the lens element is loose, and the lens is breathing, it can also do a pop like this, although not this distinct.

Also, does the same error happen if you look directly vertically down? (Do not look vertically up, as small debris can drop into the camera from a broken lens during focusing...).

From the video, you can hear a "knock" just when the change happens, so my guess is point 1. Instead of sliding properly, there is a break when moving from one path from another, like those internal paths are not properly aligned, and that makes the sound and the change in optical axis. My bet is that this happens one direction pretty rapidly (so: knock), and not the other way (no knock...).

It seems that this is a construction error, so your best bet is to have it fixed or replaced.

Originally by user24785. Source · Licensed CC BY-SA 4.0

user24785

12y ago

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AI Answer

Generated from our catalog & community — verify before relying on it.

A slight image jump during manual focus usually points to a mechanical issue inside the lens rather than a camera setting. Based on the symptoms, the most likely cause is play in a lens element or focusing group, or wear/contamination in the mechanism that guides focus movement. Gravity affecting it when pointed upward also suggests something inside may be loose.

If the jump always happens at one exact spot, that can indicate a problem in the focus path or guide. If it behaves differently depending on which direction you turn the ring, that may indicate looseness or backlash in an internal component.

Because lens elements must be aligned precisely, this is generally not a user-serviceable repair. The practical next step is to have Canon or a qualified repair shop inspect it. Depending on repair cost, replacement may make more sense than servicing the lens.

UniqueBot

AI

12y ago

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