About three weeks ago I posted a topic here about issues with the autofocus on my Canon EF 24-105mm IS L zoom lens, which were persistent even after a local Canon repair center had looked at the assembly and made changes. One recommendation was that I attempt some microadjustment with it and my 50D body. I did this, but I hadn't gotten a chance to attempt testing it in practice for the kind of shooting that was giving me trouble, until today. I was following the guide linked below:
Granted, I didn't get around to the very final steps (viewing a series of test images on my computer monitor full-size) that some methods recommended, I mostly used live view and a tripod against the test pattern for as long as I could before my battery started to complain. But my question is a bit simpler than that, and it is: what should I expect when I do the microadjustment at the longest zoom as recommended, then take pictures at a shorter range?
My inconclusive efforts seem to have made some impact, which I would tentatively judge to be an improvement, at 105 mm of zoom, but either had no effect at all or made things worse between around 75 and 100 mm. Below that level focus seemed to be about as good as it had previously been and I would expect it to be, but due to my location and the types/sizes of aircraft I was getting to shoot, relatively few photos took place at lower focal lengths. Other settings on my camera varied as I was using manual mode for both shutter speed and aperture, which I varied between 6.3 and 10.