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I have an older Canon L lens. The lens is fine other than the rubber sheath on the focus ring has come away from the lens barrel so the rubber now rotates freely. The adhesive seems to have dried and become brittle as there is clearly some residue on the underside of the rubber ring. I don't know if this was from the original adhesive or a later repair as I bought the lens second hand a number of years ago.

My question is: what is the best adhesive to glue the rubber focus-ring back in place?

I've already googled "rubber and metal adhesive", and there are many products available. But, does anyone have any real-world experience and could recommend a product to use? A generic product type, or chemical name, would be best as certain brands dominate certain markets and so may not be available in the UK (not to mention Stack Exchange's general rule about avoiding specific product recommendations).

  • Which specific lens? – Michael C Feb 25 at 1:17
  • @MichaelC: Canon 20-35mm f/2.8 L – mooie Feb 25 at 10:15
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I've never seen a Canon lens with any kind of adhesive holding a rubber focus ring on. The rubber should be "stretchy" enough that it will contract around the metal focus ring underneath it.

Some Canon lenses do have tape under the rubber focus or zoom rings, but it is not double-sided and it is not there to hold the rubber rings in place. It's there to cover access holes for adjustment and/or disassembly to give the lens more resistance to dust and weather. You're just as likely to see the same kind of tape covering holes on an inner barrel that is inside an outer barrel held to the rest of the lens by several screws.¹

If the rubber focus or zoom ring on a lens has gotten stretched or been exposed to chemicals that reduced its elasticity, the best thing to do is replace it with a new rubber ring. I would avoid gluing anything if the metal focus ring underneath the rubber ring has any access holes or screws in it. Some of Canon's L lenses don't, but many do.

The EF 28-35mm f/2.8 L has two (different) screws holding two bushings (Canon calls them "zooming collars") in holes underneath the rubber on either side of the metal zoom ring. I wouldn't recommend using any kind of adhesive there as the adhesive may well get in the holes and defeat the purpose of the bushings, which is to make the motion of the zoom ring smooth. There do not appear to be any access holes on the focus ring of the EF 28-35mm f/2.8 L, but there's always the danger that adhesive could make its way into the gaps between the focusing ring and the lens barrel behind the focusing ring and between the focusing ring and the front cover in front of the focusing ring.

¹ To see an example of the latter, scroll about 3/4 of the way down at Roger Cicala's lensrentals blog A Few Easy Lens Dustings. There's a photo of Aaron pulling such a piece of tape off the inner barrel of an EF 70-200mm f/2.8 L.

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    I guess the rubber had lost its elasticity and had been stuck down at some stage before I bought the lens as a quick fix. The rubber has definitely lost its electricity now. Due to the lenses age, I'm not sure I'd be able to get a replacement part. But, replacing the rubber would be the better option. So, if you know someplace reliable where I might be able to source a replacement, please let me know. – mooie Feb 25 at 10:30
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    From googling, I only found one seller, based in China, on eBay.com offering the part. Apart form the shipping times, this is probably fine. However, a local UK or other European seller would be preferable. – mooie Feb 25 at 10:49
  • @mooie I'm in the U.S., so my google-fu doesn't do to well at finding parts in Europe. That lens was discontinued in 1995! It was replaced with a newer model that eventually evolved into the EF 17-40mm f/4 L. I doubt the parts are interchangeable, though. Parts lists/numbers for Canon lenses are hard to find, especially those that were discontinued long before the internet thing got rolling.. – Michael C Feb 25 at 18:18
  • The part # is CA2-6784-040. I did find one seller located in San Diego, CA in addition to the couple of places in China. – Michael C Feb 25 at 18:27
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    Just ordered a replacement ring from eBay (10USD, but to arrive in two months time!). I'll post back if and when it arrives as to how well it fits. Thank you for all the help. – mooie Feb 26 at 9:38
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Usually rubber grips (such as on camera bodies) are attached using some type of double-stick tape. Replacement grips usually come with a suitable adhesive tape.

Rubber rings on lenses usually are not taped down, but are held in place by friction, as Michael C states. If the grip has stretched loose, double-stick tape should be safe for short-term use while you purchase and wait for a replacement to arrrive.

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At the automotive store - Gasket Cement or weather trim cement both will work.

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Contact cement IS the correct product Aka rubber cement Alternatively you could use double sided tape It is used for rubber grip to metal golf club dhafts and can handle lots of shear torsion force

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