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Canon EF 85mm f1.8 auto focus issue


Hi, my EF 85mm f1.8 isn't able to auto focus – it is just jumping back and forth nervously few times a second. Manual focus works ok. Has anyone had the same issue and what could be the problem?



@kanon wrote:

Hi, my EF 85mm f1.8 isn't able to auto focus – it is just jumping back and forth nervously few times a second. Manual focus works ok. Has anyone had the same issue and what could be the problem?

How far away is the subject from the camera?   Do you think the camera has sufficient light to focus?

"The right mouse button is your friend."

It does this in all focus distances and light conditions.



We are sorry to hear that this occurs.  We recommend sending the unit to Canon for evaluation.  You may fill out an online repair request form at the following link to setup your repair using our online service.

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Thanks. But this is a rather old lens and I can get a new second hand lens for quite a low price, so I was hoping that someone would know what is broken based on the symptoms and maybe I could fix it myself. For example, if it has broken motor, I've seen some replacement motors available with low cost. Would anyone have an idea what could be broken with the lens, thanks?

As you noted, this lens isn't that expensive new and certainly not second hand and because of that trying to repair it yourself has a very high probability of costing more than the lens is worth in terms of replacement cost.  The issue could be as simple as a broken trace on a flex cable inside the lens or a failure on the control board inside the lens and without service documentation and some basic test gear, you won't know until you start throwing parts at it and that will get expensive in a hurry. And if you don't have experience working on precision assemblies that like to stay clean and have a lot of fragile connections a camera lens is not a good learning experience.  Plus your only inexpensive source of parts for this lens will be from cannibalized lens on ebay or elsewhere and those come with a very high probability that the component part you buy will also be defective regardless of seller claims and when you get it you won't know if the "new" part is also bad or if the actual problem lies elsewhere. 


I just went down this road with a Canon EF-50 F1.4 that is the only Canon lens that has ever caused problems for me.  It was repaired once under warranty and again on my dime a few years later and now it again works fine but only in manual focus. The issue with the 50MM F1.4 AF is known but it isn't worth my time to repair what is an OK but not exceptional lens and I acquired a barely used Sigma 35MM F1.4 art series lens from a friend who is changing camera bodies which made more sense for me than buying another Canon 50MM F1.4 given the Sigma appears to be a very good design.  I doubt if it is worth the expense to have Canon repair your lens but if you want it done right, that is the correct option.  Otherwise replace it and save yourself time, trouble, and probably expense.


I repair a lot of complex electronic and electro-mechanical stuff down to the component level but only when it makes sense to do so (either clear cost differential or because there is no other practical option) and I have the array of test equipment and tools to do this sort of work.  But for a common piece of glass that is available used working in good condition for "cheap" it would be an easy choice for me to just replace it.



EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video

Wise words above, thank you. I actually got the lens for free from my friend, so after paying for professional service I still could end up having a great lens with reasonable costs.

"I actually got the lens for free from my friend ..."


The estimate only costs you shipping. Smiley Wink

EOS 1DX and 1D Mk IV and less lenses then before!

I've  the same issue with my Canon 85mm f/1.8.  The autofocus is jumping forth and backwards.  I've sent to the authorized thechnical assistance.  The answer was:  we are sorry, but it will cost you $ 210 to rapair it.  (a new one lens at B&H Photo costs $ 349).


The auto focus just deteriorate after 3 years, even with a low level of use and no accident, fall or colision.  It's a shame.  Consider other brands. The Canon 85mm 1.8 is really not reliable. 

I forgot to report here, but I had exactly the same answer when I took mine to be evaluated. Motor was broken. So I use it as a manual focusing lens.


I still have got nice portraits with the lens, and with 5dmkiii you'll get a confirmation when the focus is set correctly so it is totally usable lens this way too.