Recently I picked up a well-used Canon EF 600mm f4 IS II at what I *think* is a great price. The seller was very upfront on the condition of the lens and he noted that the front rubber ring on the lens had some denting "due to leaving the lens shade on overnight." I'm not quite sure how that would be, but the lens seems to be function perfectly.
As with any supertele that I have owned I purchased the Zemlin hood + cap combo (highly recommended) but unfortunately the lens cap doesn't fit well due to the denting of the rubber ring. I was able to get the cap on with some effort and as of right now I am leaving it there in the hopes, albeit how unrealistic, that it might help push the rubber ring back into place a touch. As it stands now, the Zemlin cap is really hard to put on and remove.
Has anyone attempted to "fix" the dented front rubber bumper of a Canon supertelephoto lens? I am tempted to use a pair of soft-jaw pliers to see if I can reposition the dented portion of the ring, but I don't know what risk there is in doing so. I am not sure what the 'anatomy' of the rubber bumper is or what it connects to.
Alternatively I do have a Lenshood Hoodie XXXX that would fit over the lens's glass when the Zemlin hood is in the reversed position, but gosh, those Zemlin caps are AMAZING and I'd love to be able to use it.
I'd try heating the ring with a hair dryer, while the cap is fitted. Not too hot. Pretend it's your hair that you're drying, not some kind of heat shrink thing.
I added a Zemlin ring which connects to the Zemlin hood; it kind of helps to see where the Zemlin ring pulls away from the rubber where the rubber is bent.
Would it make sense to cut a form out of something like plywood in the radius of the overall ring so that you have a way of straightening out the curve versus the single pressure point of a set of pliers?
I have this feeling that the front ring is not purely rubber. Rubber would return to its original shape--any small dent should be in its elastic region, not deformed. Is there metal or something similar underneath? Looking at the parts diagram for the v1 600mm f4L IS (I can't find the v2 parts diagram) it looks like a rubber cover over something more substantial underneath?
The rubber has a thin metal insert. I used a shifting spanner, just covered the jaws with tape, gentle bending the rubber outwards and all fixed in 2 minutes.
The rubber has a thin metal insert. I used a shifting spanner, just covered the jaws with tape, gentle bending the rubber outwards and all fixed in 2 minutes.
I had the same thing happen to me with a 300 2.8. I sent it to Canon for a clean and check as I usually do with used equipment I purchase. I made no specific mention of the dent but it came back looking like new with no additional charges (and clearly the same ring) so I know it is a simple fix. I'm not sure Canon still services that lens but It might be worth a check with Canon or other third party repair shops.
-That front ring is metal, probably aluminum, the rubber is formed rubber that slides over the front of the ring. I would not try using pliers to straighten it. It is amazing how aluminum will dent without cracking but WILL crack when you try to straighten it.
-I can't believe putting on the hood incorrectly would dent the ring, It took a hit of some sort. I bent that ring on a lens i bumped it on a door jam.
-Canon's end of service on that lens was July 2025. Although you could try calling them and see if they would replace the ring.
-If you really like using the Zemlin cap I would be inclined to use sand paper or a file to take the roundness out of the Zemlin cap in one area and when you use it, use the flattened are where the dent is. Would probably only have to do that where the bigger dent is.
Here is the EF 300mm 2.8 II front ring with rubber pulled back
jcolwell wrote:
To me, that's looks like a dent in the metal ring that's under the rubber. Leaving the lens shade on overnight would not cause this.
It looks like the hood was not seated all the way when the thumb screw was tightened down. I did the same thing on my 200F2 and now have a small flat spot. lol
Either way its cosmetic and other than that shouldn't be a worry at all, unless you're OCD about it.
Thanks everyone for the responses! Taking my time evaluating before I take any action, if any at all. To be clear, David83, I would like to use my Zemlin lens cap on the lens but with the dents it doesn't fit well. I likely will try to move it back into position at some point....
jaredmizanin wrote:
Thanks everyone for the responses! Taking my time evaluating before I take any action, if any at all. To be clear, David83, I would like to use my Zemlin lens cap on the lens but with the dents it doesn't fit well. I likely will try to move it back into position at some point....
AH, Yes! I can see how that would screw things up a bit. I use the Zemlin cap and hood kit on my 600 as well. The OE hood is just enormous
Simple fix.
First - Grow a large pair
Second - Find a small hammer
Third - Swing hammer mere mm away from front element until dents disappear using numerous small gentle taps.
Additional free advice... Don't drink any coffee or cold adult beverages before performing above steps.
If growing a large pair is not feasible, simply cut soft cloth and cardboard to fit inside to protect the front element.
lighthound wrote:
Simple fix.
First - Grow a large pair
Second - Find a small hammer
Third - Swing hammer mere mm away from front element until dents disappear using numerous small gentle taps.
Additional free advice... Don't drink any coffee or cold adult beverages before performing above steps.
If growing a large pair is not feasible, simply cut soft cloth and cardboard to fit inside to protect the front element.
Haha, I would plan on cutting out a foam circle the exact diameter of the lens' glass before trying any method. But definitely that will come AFTER my pair has grown 😜
