Tripod ring seized on my 100-400L II ........

i'll bet this is gonna be expensive!

I was using my 100-400L II on tripod and switching from landscape to portrait as I often do. I noticed that when I switched to portrait the ring would briefly hit something -- like maybe a screw underneath that had loosened.

it did this a few more times and then the lens seized between landscape and portrait. I applied a bit of pressure but it would not budge. i didn't force the issue fearing i would cause more damage.

i dropped the lens off at a nearby repair shop today and he's going to give me an estimate for repair.

has anyone else had this problem?

I have not had that problem. This may help to give an idea what has gone wrong.
The rear of the lens needs to be disassembled to remove the ring. The threaded holes in the black section are for the screws / rollers that guide and locate the ring.
I would assume one has come loose causing your problem.

ok thanks man. I thought it was something like that. what a problematic design.

Quote from Canon for a replacement ring was AU$820 and was for ring only, not the foot, or the plate that attaches with the 4x2mm screws. Supply only, not fitted.
Lens cost AU$2500. So complete ring over 1/3rd cost of lens. I can't help wondering if this was to stop 3rd parties offering replacement rings for $25 compared to the usual Canon $190 (eg 70-200 f4, 400 5.6 etc)

I think it was a cute design canon was testing out sorta like the reverse zoom of the original 24-70L (brick) which as you recall almost every one touted as a revolutionary design but really many of us who used the lens for years realized was a dud. the reverse zoom made the lens larger and heavier, made the hood the size of a bucket and had copy variation all over the map especially after the zoom loosened from age.

canon has had plenty of opportunities to use the tripod ring on other lenses but hasn't. I believe the intentions were good but the tripod ring was a dud, and as we both have experienced a weak link that has completely disabled the use of the lens.

I notice you have an aftermarket foot on yours. so do I. got mine from Kirk and it was wobbly at first and it took me awhile to realize the screws beneath it had loosened. I've had nothing but problems with this tripod ring and everytime I slide the window shut on the hood i'm reminded that I have forgotten to glue that damn thing shut or tape it

the cost to repair the lens was $195. the repair consisted of tightening all four screw which were loose. I also asked him to Loctite the screws. I would have tightened the screws myself through the foot but the ring was frozen and I didn't want to mess with it.

edit: he said there were two groups of six screws, at least that's what I understood at the time.

That seemed fairly reasonable for a factory repair, but still one could argue it was a design flaw which mean they should cover it.

It is not a wear and tear item.

I had it repaired locally. there's a repair shop a few blocks from my house. the screws probably rattled loose from all the offroad driving I do but hell it's an L lens and the screws should have been fastened with Loctite.

Well that explains the reasonable cost then.

once my car is off warranty it never sees the dealership again unless I have no choice. same goes for my canon gear.

ed rader wrote in post #18730290
the cost to repair the lens was $195. the repair consisted of tightening all four screw which were loose. I also asked him to Loctite the screws. I would have tightened the screws myself through the foot but the ring was frozen and I didn't want to mess with it.

Thanks for reporting on this problem and following up with the fix.

I noticed that both my Canon OEM Foot and the Kirk Foot were also lose and after I checked the 4 tiny, almost hidden, black coloured screws on the actual collar flange, I noticed that 2 on one side were lose. After I tightened these with a Jeweller's screwdriver (cross head), it fixed the problem.

I estimate that I made approx. 1/4 of a turn each to tighten the 2 lose screws. The 2 on the other side were snug. I'll source some Loctite locking fluid and apply to all 4 screws.

Cheers

Dennis

50 years ago camera repair people used clear nail polish. With loctite you have to be careful, most versions are for thread sizes from about 1/4 inch and larger. If you need to loosen a screw later, and you've used loctite, the potential is high that you could strip the screw head.

I always get shot down here when I say this so review the thread at https://www.photo.net …-on-using-loctite.148880/. And remember that if nailpolish doesn't work, then you can use one of the weaker loctites.

Ed,

How long have you had this lens? Lots of use?

Thanks,

Mike

I always use blue Loctite, never had a need for red.

.

John from PA wrote in post #18730416
. . . if nailpolish doesn't work, then you can use one of the weaker loctites.

.
Silicone is an excellent "keep-it-snug" solution, as well.


.