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All new on this. Bought a used camera (Canon 70D) with some lenses and are taking a thorougher look at it.

One of the lenses is a Canon EF-S 10-22mm f/3.5-4.5 USM.

The issue I am having is that it does not go below 12mm. Dial enters full stop. It operates fine in the 12-22mm range. I thought at first the markings might be off or something, but the EXIF data say 12 on pictures taken with focal set to minimum.

Exif data on 10 vs 22:

Dial at minimum:
Focal Length                    : 12.0 mm

Dial at maximum:
Focal Length                    : 22.0 mm

Some EXIF specs:

Lens Type                       : Canon EF-S 10-22mm f/3.5-4.5 USM
Max Focal Length                : 22 mm
Min Focal Length                : 10 mm
Focal Units                     : 1/mm

Set as low as it goes:

enter image description here

When unmounted, looking at the travel-path o the back part of the lens it does not go all the way up when turning down (about 14mm):

enter image description here

At 12mm (lowest I can turn it):

enter image description here


Am I missing something here, or should the dial go to 10? Could it be damaged? Anyone know if it is a "common issue"?

If it should go down to 10 is there any good idea to try to open it up? It works fine (in view of the limited expertise I have) at 12 - 22.

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  • \$\begingroup\$ Could it be that you're using this ef-s, crop frame lens on an ef, full frame body? I remember something about the flange distance differing. Maybe that causes some physical obstruction that blocks the lens from reaching 10mm? \$\endgroup\$ Jun 11 at 20:03
  • \$\begingroup\$ @SaaruLindestøkke: No, it's on a Canon 70D. \$\endgroup\$ Jun 11 at 20:04
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    \$\begingroup\$ If by "open it up" you mean disassemble it to see why it doesn't go down to 10mm, I'd say that if you have to ask that question, then you shouldn't be doing that. \$\endgroup\$
    – Peter M
    Jun 11 at 22:57
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    \$\begingroup\$ I agree with Peter that it's quite risky to open up lenses, but if you really want you could check out some youtube videos. E.g. this one shows the lens assembly inside, perhaps something got stuck there and is blocking you from going below 12mm. If you decide to dissassemble it, expect that you might not be able to re-assemble it. \$\endgroup\$ Jun 11 at 23:25
  • \$\begingroup\$ Yes. I have disassembled one earlier to remove a foreign object, and though it went OK, it comes with it's risks of course. \$\endgroup\$ Jun 12 at 6:19

2 Answers 2

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I don't have an EF-S 10-22mm lens to play around with, but I do have an EF 17-40mm that is more or less the FF equivalent lens. Looking at the block diagrams of both at the Canon Camera Museum, they're very similar in terms of optical formula. They were also introduced only about one year apart.

To get to 17mm, the widest angle of view, the EF 17-40mm moves the rear group all the way to the back of the lens. I would expect the rear group of the EF-S 10-22mm to also move all the way to the back of the lens for 10mm.

It may be that something is out of place between the rear element and the front of the PCB in the back interior of the lens. But more likely is that one of the plastic/nylon rollers that follow the grooves in the zoom helicoids has become deformed or come partly apart and his getting stuck at 12mm.

Since you've indicated that you've been inside lenses before, you might want to take a look inside the back of the lens. Please be warned:

  • This is risky, and could ruin the lens if done improperly!
  • If things go wrong, you might change a lens that is usable from 12-22mm to a lens that is not usable at any focal lengths. Things will sometimes go wrong.
  • If you give up and decide to send it to a repair shop disassembled, they'll almost certainly refuse to work on it. If they do agree to look at it, they'll charge (a lot) more than if you sent it in without being taken apart.
  • If you break/strip/tear something inside and then put it back together as best you can before sending it to a repair shop, they'll be able to tell when they get inside the lens and will almost certainly refuse to work on it. If you want them to send it back to you they will likely bill you for the work they did opening it up and putting it back together the way they found it. If they do agree to continue, they'll charge (a lot) more that if you hadn't taken it apart, broke something, and then reassembled it incorrectly.

This YouTube video shows a disassembly and reassembly of an EF-S 10-22mm lens. However, I would strongly advise you to remove the two screws holding the communication contacts with the camera in place on the inside of the flange ring before loosening the screws that hold the flange ring to the rear of the lens.

Be very careful when disconnecting the flex cables from the PCB! If you damage any one of them the lens will essentially be toast. Mark the alignment of everything you remove before you remove that part. I'd also remove the rubber focus ring cover before removing the rear barrel and then wait until I had the rear barrel back on the lens to replace the rubber focusing ring. Removing and installing it with the rear barrel removed risks damaging one of the flex cables as you pull it past them.

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  • \$\begingroup\$ Thank you for a detailed answer. Yes, I dismantled a 17-85 Canon lens and that went OK (AFAIK ;P). Biggest issue was to get the black inner ring out (The one holding the communications contacts in place). Problem with that lens is that it fails with aperture above 4. For the lens in question, after some back and forth + test-shooting, I'll leave it be as long as it works in the 12-22 range, and only open it if more issues arise. The "rollers" hypothesis sounds likely. I can comment back if I ever open it up. \$\endgroup\$ Jun 16 at 20:16
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    \$\begingroup\$ The 17-85mm failing above f/4 is almost certainly an issue with a flex cable that has lost continuity between the PCB and the aperture mechanism. \$\endgroup\$
    – Michael C
    Jun 19 at 7:46
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The photo you posted shows you have a filter installed on the front of the lens.

This lens has a front element that moves forward as you zoom to 10mm. The filter threads may be restricting full movement. Try removing the filter and see if that allows full movement.

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  • \$\begingroup\$ Thank you. Good eye :) I tested with the filter off, but no difference. The front lens has no visible obstruction points and there is a few millimeters left until it would have reached the outer most dead stop. \$\endgroup\$ Jun 16 at 20:23

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