I had some jostling of my luggage coming back from a trip recently, and sent the body and three zoom lenses in my sig to a very reputable shop recommended here. When they returned, I checked them with Lens Align Pro to get a baseline for the future if they get banged around again.
When I've had calibration donw by Canon, the two ends of the zoom on each lens were within 0 to +5 on microadjust. When I checked the 24-105 and the 16-35 now, the difference at the zoom extremes is 0 to + 8 for both lenses. All done at 50x focal length, ISO 100, lowest f/stops for each lens.
I've seen very good reports from multiple members on this private repair shop and when I spoke to the owner initially, he said his specs for calibration are tighter than Canon's, and that I probably would need no microadjustment for the lenses when he was done.
This appears not to be the case. He's away on vacation now. I must be missing something, and I just wonder if anyone has an insight here.