Ok folks, here's one I haven't come across before: I recently purchased a Canon 70-200 f4L lens in (seemingly) great condition. Yesterday I was shooting pics of birds in a group of trees several hundreds yards away. As I swung the zoom all the way to 200, the auto-focus started having trouble locking in and just kept on trying but not achieving focus. I took it off "auto" and put it in manual, and of course it focused beautifully. So it's not the glass. I then played with different zoom settings, and found that auto-focus had no issues up to about the 135mm spot, and also at much shorter distances. At this point I was unsure if it was the lens or the camera so I took the lens off the camera (a 1DS MkII) and put it on my Rebel XS, and the lens still was having trouble. To test further, I put my old consumer lens, an EF 75-300 f4-5.6II to the 1DS and it slammed quickly into focus at all distances and zoom positions. I've since gone on line and found it could be anything from dirty contacts to needing the sensor cleaned, but I thought of posting here today just in case someone out there has previously had a similar experience. I'm new to the forum and would appreciate any ideas. Thanks.
hmm..this scenario sounds like a very common problem with the 17-85mm lenses. Turns out the aperture flexi cable inside gets damaged & needs to be replaced. I have one, need to gather the nerve & get quality screwdrivers before opening her up. Haven't heard about this scenario with your lens though but just did a quick glance online and there appears to be a good few cases of a slightly different issue with your lens' focus mechanism..solution for which would be to change the USM unit? Give a look online. www.dpreview.com/forums/thread/3347211 this may help www.ebay.com/itm/Canon-EF-70-200mm-f-4L-IS-USM-Focus-Assembly-AF-Focus-Motor-Replacement-Part-/332155448634
Thanks for the feedback, guys...alas I took it back to the store, who carries a 60-days guaranty on used purchases. They are sending it in to Canon to be looked at. Won't cost me a dime, and I should hear something back in 2-3 weeks. I'll bring you up to date at that time. Thanks again very much! Richard V
I would be interested to see if someone can repair a lens with a broken flexi cable. I have a Sigma 24-135mm with this problem. I am considering giving it away (or throwing it away) but if it can be fixed maybe I will have it repaired.
Hello Robert, a quick look on fleabay shows that the cable you require is easily available & at a very low price. If you are a DIY tinkering type, would be worth it to open it up yourself. Always helps to takes loads of photos or videos of the whole disassembly process, also make notes, draw layouts of screw locations, etc. I myself am learning through experience & have opened just about 7 old vintage lenses, successfully cleaned & put back together.. In my learning, i have killed 2 lenses...one i still can't figure out the combination of lens elements to get it working right & the other a cz with the tension ring(which i had no clue about..lol..these amateurs eh....haha)...can't fit it back together..i do regret i opened that one up without prior knowledge. Finding someone to fix yours really depends on where you are located. I know someone here in eire who is well versed with lens repairs & charges a fee.
I am not accomplished at DIY, while I have managed to fit some new light seals to my old K1000 with reasonable success, I have managed to kill a teleconverter that I opened up to clean some dust off the glass. I must try every combination of the lenses again till it works. Soldering a new tape into the lens is well beyond my ability and courage. I am in Hampshire, England, so would hope to find somebody over here that might be able to replace the flexi tape. I currently don't have a Canon digital camera but am always looking out for a bargain and would like to be able to use this lens as it gets good reviews. I sold my Eos 10D and Canon 70-300mm IS to fund the purchase of a Pentax K-5, wish I had kept the lens it was great in comparison to the Tamron and Sigma budget lenses I use on my K-5.
Well, i'd say in the UK would be even more easy to find good repair people...a quick ggle search online now got me a few results...one based in surrey with a quotation online of £45 for aperture repairs..that maybe is a bit much for the lens you mention as i'm not sure the value..but a nikon fit of the same went sometime ago here in the used sales for about 100euros. Do go through a few shops though, try to speak by phone or if close enough of course visit & only then make your choice. Better to not have anyone open it up than someone not careful & efficient...(like me with my CZ..hhaha..little lightheaded jokin here anyways...it definitely taught me a thing or two..& that's valuable..eheh) And if not, maybe someone experienced & close to you comes on here to the forums & lends a helping hand !!!
Thank you for looking in to it. I did get a quote for a plastic bayonet repair at a well known repair house here in England, plus a quote for the parts for me to have a go myself on an Olympus 4/3 lens that my great niece has. It worked out cheaper to by a 2nd hand lens from them so I did that. You are right about the lens repair cost of £45 (when added to the £35 I paid for the lens) being more than it might be worth to me. I might offer it up free in the forum for someone that would like to have a go at repairing it themselves.
Thank you for your response and also that link for the new USM part via eBay. I checked with my local camera store and found out they approved the repair amount to Canon, and I should have the lens back in about a week to ten days. I have book-marked the link you sent for future reference though. Thanks again very much... Richard Vaara Everett, WA
Hello Marcus, and sorry I did not respond earlier to your question. The light was broad daylight, on a sunny day. I was shooting at a high angle to the tree tops against a bright blue sky...normally a no-brainer even for my older Canon AF lenses. The AF was just not locking on to the image in the viewfinder; my local camera store checked it out too and called it "chattering", as the lens was basically going in and out only a few millimeters trying its darndest to lock on. And no, when I went into manual, I did not get the focus beep tone or confirmation of focus. The camera store did approve the repair amount to Canon and I should have my lens back in about a week or so. Hopefully I will also be told what the issue was, for my own information. Thanks for your question, Marcus. Richard
