Max brunell , Feb 02, 2012; 10:49 a.m.
I just noticed there is a crack in the barrel of my 70-200mm f4 IS lens. It is really close to the metal mount where it mounts to the camera. It looks like a hairline crack that runs from side to side, about an inch in length. It does not run the lenth of the lens, but the width.
The mount looks fine, it mounts to the camera fine, it seems to take pics fine. I bought this lens used and didnt see the crack nor was I told about it from the seller. I never dropped it but apparently someone did or something.
What should I do with it? Is it definitely damaged on the inside ( like the lens elements) if there is the crack on the outside?
Thanks
Mark Sanderson , Feb 02, 2012; 11:02 a.m.
Take some photos and see if the lens works - if not, return it to the seller if that is an option.
Perhaps it is just a cosmetic crack in the paint on the lens and may not affect the functioning.
Max brunell , Feb 02, 2012; 11:03 a.m.
The pics that it takes look fine. Its definitely not just the paint.
Sarah Fox 
, Feb 02, 2012; 11:04 a.m.
Sounds like a manufacturing defect. Weird.
I'd send it in to Canon service. I wouldn't be surprised in the least if they repaired it for you for free. If it were a consumer lens, maybe, maybe not. However, this is a professional lens, and we therefore expect superior construction for all the money we pay for it.
Marcus Ian 
, Feb 02, 2012; 11:05 a.m.
I would send it in to Canon. Obviously the housing will need to be replaced, but, as the lens is still fully functional, there likely is little else that will need to be replaced. The repair will be several hundred, but, considering the likelihood that the crack will propagate over time, it's only going to get more expensive. The added benefit is that you'll get a 'free' calibration and cleaning with the replacement of the outer housing.
OTOH, you could just push it, if you choose to do that, I would abrade (down to the metal) the area around the crack, and use an epoxy (such as jb-weld) to reinforce the area over and around the crack. Obviously that will diminish and 'resale' value of the lens, but won't allow the damage to progress... you could even do that temporarily, as it won't increase a later repair cost (as long as you are careful!).
Sarah Fox , Feb 02, 2012; 11:14 a.m.
A *crack* in the metal (vs. a bend) suggests a defective casting or extrusion. Even if Canon didn't own up to the defect, I doubt the cost could rise as high as several hundred. I've read of broken apart lenses (busted housings) being repaired for maybe 200-300. Again, though, Canon has different standards for pro gear. They've got a reputation to defend. I bet the repair is gratis.
Max brunell , Feb 02, 2012; 11:20 a.m.
Wayne Campbell , Feb 02, 2012; 11:31 a.m.
"How hard is it to take the old one off and replace it with this?"
Probably not too hard if you don't mind 10,474 loose parts spread out on the dining room table!
Robin Smith 
, Feb 02, 2012; 11:57 a.m.
Take some test snaps, and see if the barrel bends or wobbles. If no bending and the shots are good forget it and carry on using it. If the shots are bad or it bends then you'll need to get it fixed: could be pricey.
Puppy Face , Feb 02, 2012; 11:59 a.m.
While the main barrel is metal, I think this sleeve area is plastic.
