I own a couple of Canon 1D MIII bodies and a couple of Canon 70-200mm f/2.8L IS lenses. Back in May I sent the bodies to Canon for a hardware "fix" for certain autofocus issues. Then, near the end of July I shot Jewel in concert and noticed a definite autofocus issue that couldn't be corrected with microadjustment ... I did several microadjustment tests with both the failing lens and my backup lens on the body that I normally shoot with using that lens. I sent the lens back to Canon for repair. $180. Seems OK now but they made a note about sending the body with it if there were more problems.
Last week I shot Toby Keith with the same body but using the backup lens ... note that the backup lens is actually newer and is not a backup in the sense that it isn't as good ... I normally keep it on my 1Ds MIII body in my studio. The images were very soft even though when I did my tests earlier it was fine! So, I thought maybe it was the body after all, although that seemed odd since it was just at Canon. What to do? A series of tests. I blocked out an Excel spreadsheet where I would shoot both lenses at small and large focal length on both bodies. Coincidentally, I started with the body that I don't usually use this lens on. All tests on both lenses were good. I thought, "Aha, it is a bad body!" So, I mounted up the "bad' body on the tripod with the "bad" lens and started through the microadjustment process. "Oh, Crap!" There was the problem ... I had left the microadjustment set to +20 for that model of lens. Although I had used the body for another project, I had used a different lens, which had not used the MA, so it worked fine!
So, I corrected the microadjustment for the lens, which turned out to be +4 and will try it out on the Reverand Al Green on Thursday night. Next time, when the facts don't fit I will try to think outside the box. So, I am embarrassed and relieved!
Travel Safely,
Dwight
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