Canon 85mm both front and back focussing issue ?

[Andrew Davies Photography]

I have a Canon 85mm 1.8 purchased from a certain auction site some months ago. Since getting it i have been unhappy with the focus results.

I have tried adjusting technique whilst hand holding and also been through the moire and ruler tests to attempt an adjustment.

Today i tried the battery test with 5AAs at 45 degrees to the camera on tripod 2 second timer centre spot focus.

At around 1 metre i had to dial in -20 ( the max ) on my 5D3 and -10 on my 5D2 to get it spot on, it then performed perfectly even off the camera at that distance.

I them aim it into another room at a wall clock about 4 meters away and now its front focusing and i have to return it to zero on both cameras to get it in focus.

This has left my head hurting and not sure what to do with it ( bar throwing it in a bin )

Is it possible for a lens to both front and back focus depending on the distance if so is this a mechanical fault that can be repaired does anyone know ?

thank you
Andrew

Wedding Photographer Durham Darlington Teesside Newcastle York

 

[ajfotofilmagem]

If AFMA has not had consistent results, the best thing to do is to send to Canon to calibrate.

 

[Andrew Davies Photography]

If AFMA has not had consistent results, the best thing to do is to send to Canon to calibrate.

That would require sending both camera bodies and the lens which in the middle of the wedding seasons not an option plus the cost of the lens being only 200 quid is not worth it they will charge for the calibration.

 

[mackguyver]

I had a 135 f/2 that would do that and it drove me nuts, too. I ended up sending in my camera & lens for separate issues, but Canon was nice enough to calibrate them together. The paperwork that came back indicated that the calibration was probably not what fixed it, however. It said something like "lens optical alignment & calibration" followed by the camera repair then "camera & lens combination calibrated together" or something like that. Your lens might just need an optical (re-)alignment, but the repair cost may be hard to justify depending on how much you paid.

 

[sdsr]

This is a tangential point that won't help Andrew one bit, but this thread, and the similar recent one re the 50mm 1.4, remind me of one reason why I look forward to the time (I hope it comes) when Canon makes a useful mirrorless camera, thereby rendering this back/front-focusing menace obsolete.

 

[sagittariansrock]

Not worth paying for calibration.
I had similar experience with a 50mm/1.4 (which was fortunately systematically front focusing at least, therefore correctable by AFMA- so I could sell it with a clear conscience).
I think I am done buying fast lenses without warranty, whether Canon or third party.

 

[Andrew Davies Photography]

Took it out again today after perfecting AMFA at home at -10 on the 5D2

Heres the results
http://weddingphotographernortheast.blogspot.co.uk/

Yet i had to go back to 0 to get it sharp - go figure ??

 

[Mt Spokane Photography]

Took it out again today after perfecting AMFA at home at -10 on the 5D2

Heres the results
http://weddingphotographernortheast.blogspot.co.uk/

Yet i had to go back to 0 to get it sharp - go figure ??

I noticed that you indicated that you were adjusting it handheld. That's not going to give good results, and many methods rely on your vision to select the sharpest image, which adds another variable. Then, the 50mm f/1.4 is well known for inconsistent autofocus, so its never quite in the same place on each photo.

Put all these together, and you will be tearing your hair out.

Here is something to read concerning the complexities of trying to get accurate AFMA, and gives you some information as to why so many struggle.

There are a ton of factors to consider, something as simple as image content will cause a shift in autofocus.

 

[Andrew Davies Photography]

Took it out again today after perfecting AMFA at home at -10 on the 5D2

Heres the results
http://weddingphotographernortheast.blogspot.co.uk/

Yet i had to go back to 0 to get it sharp - go figure ??

I noticed that you indicated that you were adjusting it handheld. That's not going to give good results, and many methods rely on your vision to select the sharpest image, which adds another variable. Then, the 50mm f/1.4 is well known for inconsistent autofocus, so its never quite in the same place on each photo.

Put all these together, and you will be tearing your hair out.

Here is something to read concerning the complexities of trying to get accurate AFMA, and gives you some information as to why so many struggle.

There are a ton of factors to consider, something as simple as image content will cause a shift in autofocus.

It wasnt hand held all adjustments were made with timer on tripod at home and were accurate , then out in the field it changed again