17-40 - lateral jump in LV. Normal?

It's only been 16 months since I got the 5DII so, in an idle moment, I thought I'd have a bash at this micro-adjust malarkey. I did it by the book and the 24L and 35L both showed as being spot-on - zero adjustment required.

Then I tried the 17-40 at 17mm and was surprised to find it needed -13. Double-checked; yep, -13. I was surprised since I hadn't noticed any focus problems. But I suppose the focus tolerance at 17mm is quite substantial.

No the real problem was a sideways shift in the image in LV when adjusting the focus. At the x10 magnification, the lateral movement was around 1mm on the screen. And it was consistent - every slight movement in either direction gave a small jump.

Question - is this normal? A small slackness in the focus helicoid, a mechanical tolerance that can be ignored? Or should I be whipping myself up into a frenzy of angst? I'd prefer not to.

This sounds very weird. Can you explain it again? It sounds like the image being refracted through the elements of the lens is actually shifting laterally as you run the focusing element back and forth while you turn the focusing ring back and forth??

Mine does the same thing, but then again, mines been through hell.

Adharr wrote in post #16805489
This sounds very weird. Can you explain it again? It sounds like the image being refracted through the elements of the lens is actually shifting laterally as you run the focusing element back and forth while you turn the focusing ring back and forth??

No, it's more like the internal focusing helical that holds the element is shifting as it's moved. At least, that's what it looks like to me.