xpfloyd wrote in post #16193767
Square to the target is just based on Canons guidance for MA. I know there are third part MA setups that say 45 degrees to the target but I personally cant see how that would help. That's a recipe for driving you insane. At least when the camera is square to the target and your test shot is OOF you know you have an MA issue. If you are taking AF shots at a target that's at 45 degrees at f/1.4 all it takes is for the camera to focus slightly further up or down the 45 degree slope and your shot will look OOF due to the narrow DOF (depending on how close you are testing), you will then think its the MA when its actually the focus position.
I should point out that this is just what I think and don't have any technical knowledge to back it up, it just makes sense to me.
What I will say though is that your problems were exactly like mine and now my lens is perfect at every aperture and every focus distance. If I was you I would buy the dock and be done with it.
Yes, the focus target should be at a constant distance from the camera so the size of the AF point doesn't matter, i.e. the focus point can't accidentally lock on to something further away or closer away.
But it is nice to have a slanting subject somewhere outside that focus target, so you get a focus scale where you can see if the lens is front- or backfocusing.
With just a target that is at constant distance, you don't know if your adjustment has peaked at the optimum without testing adjustments in both directions. With a 45-degree focus scale to the side of the focus point, you can see if the sharpest region is at distance zero relative to the focus area or if you can see better focus further away.
Just note that before doing this, it is good to verify that the lens isn't decentered so one side of the image is sharper than the other side.