Auto-focus doesn't give pefect results

[AnasTB]

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 !

[cicopo]

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.

[AnasTB]

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"

[kvbarkley]

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.

[lly3988]

60D has no afma feature.

[kvbarkley]

Oops, I thought all cameras above rebels had it.

[lly3988]

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.

[AnasTB]

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.

[lly3988]

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.

[AnasTB]

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