100-400 test shots.

After power diaphragm replacement. Can be done at home without any special tools.

Well that's a lot more lens parts than I have ever uncovered in a project! Total tear down. Wow.

Looks like it paid off.

Perhaps you could post a step by step walk through for us?

You sir are a brave soul.. I dont think I would ever tear one apart like that. Looks like it went back to gether well. Congrats..

CyberDyneSystems wrote in post #15900125
Well that's a lot more lens parts than I have ever uncovered in a project! Total tear down. Wow.

Looks like it paid off.

Perhaps you could post a step by step walk through for us?

Thanks. I don't think I can. Firstly I hate writing and lack proper terminology. I have made a few mistakes. I should have taken the lens apart after getting the diaphragm and not a month before - it would have been much easier to remember all the steps. There's very little info available. I've found one post here on POTN in the lens section about partial teardown https://photography-on-the.net/forum/showthre​ad.php?t=948918. One link to some guy's repair shop http://www.jemapela.co​m/?cat=13 and a PDF doc. showing a technical drawing of the lens with a parts catalog http://www.f20c.com …204.5-5.6L%20IS%20USM.PDF which turned out to be most helpful since it shows all the parts in relation to one another. I've made little sketches of various sections to place the most crucial parts - collars and screws. But took only a few cell phone shots at the very beginning, primarily of the PCB connections. I'm tempted to see if I can improve the sharpness by adjusting the front element.

Nice photos .. looks like all that effort paid off nicely!!

You have my full respect Val
PS
Love your avatar photo

I'd never have the courage to pull my 100-400 apart. Especially now that I see how many parts there are. Whenever I try something like that, little springs always pop out unexpectedly, fly over my shoulder and then vanish somewhere in a dark corner of my room

Perhaps you can post a "How To".

Mike

I tried to put a kit lens together before and failed to figure it out and I'm a mechanical designer. Good job!

Jim_T wrote in post #15901353
I'd never have the courage to pull my 100-400 apart. Especially now that I see how many parts there are. Whenever I try something like that, little springs always pop out unexpectedly, fly over my shoulder and then vanish somewhere in a dark corner of my room

I found one of them yesterday when I was cleaning a bookshelf. Would you like it back?