Today, I'm very happy!
I've been having a lot of problems with the Auto Focus for my 5DmkII & the 50mm f1.2L. Of course, I was advised to upgrade to the 5DmkIII (because the lens was 'made for it') but my budget does not stretch that far.
I went to Specsavers & also bought the Precision Matte focus screen which improved the Manual Focus but Auto was still out. I then tried the manual Northlight Microadjustment method for correcting the AF.
http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html (http://www.northlight-images.co.uk/article_pages/cameras/1ds3_af_micoadjustment.html)
The resultant correction factor was -20. Still the focus was out & I was tempted to send both to Canon for recalibration.
Two minutes with the Magic Lantern dotTune & the lens was recalibrated to a -7 correction factor. Test so far show good results.
Thank you for all the hard work!