topic Re: Auto-focus doesn't give pefect results in EOS DSLR & Mirrorless Cameras

Auto-focus doesn't give pefect results

AnasTB — Thu, 29 Jun 2017 16:05:20 GMT

Hi everyone,

I have a canon 60D + 50 mm 1.4 canon lens.

I bought two of them ; but the focus of the lens ( Auto&manual) was not working because of barrel ring deformation.

So, I purchased the part from internet, manual focus works now perfectly. But, the autofocus does not give perfect results. If I zoom while autofocusing, the camera skip the perfect focus and stop focus on a blurry image.

So, what do you think ? could the problem be from the ring or the motor of the lens? and of course, I hope it's not a camera problem...

Thank you very much !

Re: Auto-focus doesn't give pefect results

cicopo — Thu, 29 Jun 2017 17:16:40 GMT

Don't know what you're talking about when you say "when I zoom". It isn't a zoom lens. Sounds like you are the problem by using the focus ring when also using the AF.

Re: Auto-focus doesn't give pefect results

kvbarkley — Thu, 29 Jun 2017 18:18:29 GMT

I think the Pottery Barn rule applies here.

SInce you took the lens apart and put it back together, we have no idea what might be wrong.

SInce you have a 60D, you can use AFMA to adjust things between the camera and the lens. In fact, if you had AFMA set before, that might be the issue now.

Re: Auto-focus doesn't give pefect results

lly3988 — Thu, 29 Jun 2017 18:58:25 GMT

60D has no afma feature.

Re: Auto-focus doesn't give pefect results

AnasTB — Thu, 29 Jun 2017 19:04:23 GMT

I'm talking about digital zoom, two buttons on top right of the camera, the zoom is just to check focusing !!!

No, I use manual focus when the button on the lens is on "MF"

Re: Auto-focus doesn't give pefect results

AnasTB — Thu, 29 Jun 2017 19:06:49 GMT

I have no idea about the AFMA and I don't know if my camera has it. How to check that ?

Re: Auto-focus doesn't give pefect results

kvbarkley — Thu, 29 Jun 2017 19:38:23 GMT

Oops, I thought all cameras above rebels had it.

Re: Auto-focus doesn't give pefect results

lly3988 — Thu, 29 Jun 2017 23:38:59 GMT

50D, 70D and 80D have AFMA but not 60D

BTW, if the image looks blurry when magnified, it could be motion blur or lens not accurately calibrated.

Re: Auto-focus doesn't give pefect results

AnasTB — Fri, 30 Jun 2017 08:48:31 GMT

I don't think it's motion blur, because the autofocus result is the same even with static object.

How can I calibrate correctly my lens ?

I will add a video showing the operation of the autofocus, I think that can help explaining the situation for you.

Re: Auto-focus doesn't give pefect results

lly3988 — Fri, 30 Jun 2017 12:10:41 GMT

No, you cannot calibrate the lens up to factory standard by yourself. Even the slightest adjustment of the screws on the helicoid will change the tilting angle of the glass elements of the lens. Improper installation will as well cause trouble.Check if you have over-tightened some screws.

I am a big fan of DIY repair. I found it not so hard to replace parts in cameras.But for lenses, it is a lot more complicated especially when you have to go beyond touching the USM and helicoid etc.

REPAIRING LENS IS NOT JUST ABOUT REMOVING SCREWS AND REPLACING PARTS.

Send it to Canon or use it as manual focus lens and focus in LV.

Good luck to you.

Auto-focus doesn't give perfect results (Video added)

AnasTB — Sun, 02 Jul 2017 15:16:08 GMT

Hi,

I'm back to you. This is the video that explains my problem: https://youtu.be/WjuwABW_nzU

I'm using AF on the first part, and the MF on the end.

My first topic:
http://community.usa.canon.com/t5/EOS/Auto-focus-doesn-t-give-pefect-results/td-p/212680

Re: Auto-focus doesn't give perfect results (Video added)

Waddizzle — Sun, 02 Jul 2017 15:58:58 GMT

If you took your lens apart and made some sort of repair, you are on your own. I cannot advise you on what to do, and I don't believe many others around here can, either.

Re: Auto-focus doesn't give perfect results (Video added)

lly3988 — Sun, 02 Jul 2017 17:01:34 GMT

I suggest you mount the camera w/lens on a tripod when you are testing. Then take some pics in both AF and M/F modes and see the results. See if the pics taken with AF are blurry. Try step down to F2.8 and F4 and see the results.

You are holding the camera with your shaking hands and magnifying the view makes testing very unreliable.

Test it in a well lit enviroment with a target with good contrast.

In your video the first beep confirmation comes with an in-focus image. The second one comes with a blurry image. But it cannot proof anything.

If after proper set up, the lens still cannot focus accurately, send it to Canon. Or simply use it as a manual fcous lens.

Re: Auto-focus doesn't give perfect results (Video added)

AnasTB — Mon, 03 Jul 2017 14:16:43 GMT

I aprreciate your healp, thank you 🙂

Re: Auto-focus doesn't give perfect results (Video added)

AnasTB — Mon, 03 Jul 2017 14:52:42 GMT

Even on a tripod it doesn't give perfect reuslts ..

I see that it's not a simple issue, so thank you very much and I aprreciate your help. .

Have a good day !