Anyway, I completely agree that the best recourse is to send the thing in for professional repair. However, if you want to try self-rescue first/instead, then this would be the first step. (As you can tell, I'm no artist.)
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Thanks a lot for your great help Brian!! I will save those tips for later use (hope not though)
I sent the picture, I posted here, to the repair centre of the shop were I bought the lens as well. Just got their answer: send it to Canon to have it completely checked, internal mechanisms etc!!!
So there it goes.
Look like the lens edge (where the thread is) is caved in from the impact. I like "sirimiri" in-depth suggestion, start by taking out/breaking out all the filter's shards, except if you have dremmel drill fitted with a small circular saw, and a steady hand,it is probably easier to circular saw the filter at two or more opposite point, and then just grab the broken filter out in 2 pieces. The thread for the lens is probably useless since the outter edge is no longer a perfect circle, so all in all, canon may have to replace the thread part of the lens or the whole outside casing for the lens. Just my 2 cents.
Y'all got to be friendly with your local repair shop. We do this "repair" for free, and it takes two minutes. Our repair tech uses a band wrench and a small rubber mallet. The glass WILL NOT damage the lens front element unless you hit THEM with the hammer . I have seen thousands of these filter jams in the last ten years and all have been easy and quick fixes for free.
JackF wrote:
Thanks a lot for your great help Brian!!
You're most welcome.
Off topic; I didn't look at your profile until I saw your use of "centre" instead of the American "center." I've never been outside North America, but if I ever get the chance to visit Europe, the Netherlands is high on my list of places I want to see.
The only Nederlander I know (and not well) is Maarten Pieters, the director of WOSTEP (the Watchmakers of Switzerland Technical and Education Program), who -- while he was assistant director -- was one of the examiners at my certification test.
And, of course, the actor Jeroen Krabbé, who has been in a number of American films.
Anyway, good luck with your situation. I'm sure the Canon technicians will take good care of you.
I think there is something else that needs repairing here.
That is your friendship.
The BEST solution (IMHO) is to send the lens to a THIRD PARTY (canon or local camera shop) so THEY get the responsibility for telling the butter fingers friend that there is ANY damage and WHATEVER amount it may cost.
IF you use the THIRD PARTY as the "ruling judge" then YOU will do better in preserving YOUR FRIEND and....in my POV....true friends are much more valuable than ANY lens.
That is what I would do.
Then...when all is settled....You can ask HIM for a favor to REALLY clean the slate...such as borrowing his Ferrari for a nice weekend drive in the country....or something like that.
OMG .. is that my lens ? that is exactly what happened to my 17-40 with the filter on ..
but .. what i did was remove all the broken glass and use some really strong shears to cut the filter and use a large piler to bent them inwards .. and off it came
Well, a 20D ain't worth all that much these days moneywise, despite being a very capable body. I sold mine in January for $300, the minimum cost at Canon Canada is $180 for any fixes it seems. So it may be easier if you suspect the body to buy a "new" one outright.
. I have seen thousands of these filter jams in the last ten years and all have been easy and quick fixes for free.
that is exactly what happened to my 17-40 with the filter on .. 
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