<span style="font-size: 9pt; color: black; font-family: Verdana;"]I spent most of the day performing micro adjustments on all of my lenses and my two camera bodies. I learned a lot from this experience.<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]Camera bodies: 50D and 1D Mk III<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]Zoom lenses: 1) EF-S 10-22 f/3.5-4.5, 2) EF 16-35 f/2.8L, 3) EF 24-50 f/2.8L, 4) EF 24-105 f/4.0L, 5) EF 70-200 f/2.0L.<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]Prime lenses: 1) EF 50 f/1.4, 2) EF 85 f/1.2L, 3) EF 100 f/2.8 macro, 4) EF135 f/2.0L<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]First off, this was a big job and took a lot of time to do it right. There is a bit of a learning curve to go through but once your set up right and can verify the results with repeatability then you know you got the hang of it.<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]Zoom Lens are difficult because of the optical complexities inherent to them. The short side of the focal range can perform much different from the long side of the focal range. You have to strike a compromise or a happy medium. Of the 5 zooms that I have 2 were really sweet and performed consistent through out the whole zoom range. These two lense were the EF-S 10-22 and the EF 24-70L. Both of these lenses needed very little micro adjustment + 3 for one and -2 for the other. By far the worst performing zoom was the EF 70-200L it needed -14 on the 70mm side and + 5 on the 200mm side. I ended up setting the micro adjustment to -2 as the best overall setting.<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]The prime lenses were easier to adjust than the prime, as you would expect. The one discovery I made was with the EF 50 f/1.4 lens. I found that at times it demonstrated hysteresis. If it had to auto focus from a longer focus to a shorter focus it would bias with forward focus of about +11 and if it auto focused from a short focus to a longer focus it would be spot on repeatedly. I will experiment with this lens one more time on another dayto make sure that these results are repeatable again. If it is, then I will send the lens into the canon service center.<o></o>


<span style="font-size: 9pt; color: black; font-family: Verdana;"]I learned a lot from this effort and the optical performance improvements is noticeable with optimum micro adjustments especially with fast primes (the 85mm 1.2 is razor thin and good location of focus is a requirement). I have not been please with the performance of the 70-200L since I purchased it and always thought that it was operator error. Also, I had a hunch that something was amiss with the 50mm 1.4 at times. Had I not performed this micro adjustment processI would have never discovered these anomalies.<o></o>





I recommend the following reference for performing the micro adjustment procedure:


http://www.imaging-resource.com/ACCS/LA/LA.HTM


Kyle