Returning or having Canon calibrate a new lens?

[dwdong]

Hi,

I have just ordered and tested two new Canon 35 f/1.4L lenses.  First one backfocused, second one front focused.  Tested at f/1.4 and f/2.0 using batteries, a receding fence and a face.  Also tested on both my 40D and Rebel XT.  Test conducted both handheld and on tripod with cable release.  I have returned both to Amazon for exchange (they ship replacement overnight, excellent service).

Is this the recommended procedure to get a decent focusing copy?  Or should I send a new lens to Canon for calibration at the cost of turnaround time and the risk that it will still not acceptably focus (and maybe no longer be returnable to Amazon)?

To anticipate a few questions, I have experience with 24-105L, 85 f/1.8, 70-200 f/4 L (both versions), and 135L.  All focused correctly under similar test paces.

Thank you for any advice you can offer.

Dave

[tunahunta]

Hi I had to bring my 24-105 L to an authorized canon factory repair facility . It needed  to be "tweaked" (whatever that means).    The images are  now noticebly sharper. I guess it is true.