Her are the screen shots of 2 shots of Bart's Slanted Edge target, both taken with my new a7r and a Contax Planar 1.7/50 at f/8, distance 40*focal length = 2 m, 372 with 1/10 sec, 303 with 1/8 sec.
One was shot with the camera on a Gitzo 1531, weight 1050 grams if memory serves me (sorry I have no weight at hand), a Fanotec Ezy Leveler leveling base (250 gr ), an 800 gr Linhof 3-way head and an original Arca Swiss dovetail clamp. No extension of the centre column. The tripod was burdened with a backpack containing 3 ½-litre bottles of beer. Alcohol-free beer, so the tripod would not sway for that reason :-)
The other test image was shot from a Gitzo GT 0530, weight 700 gr, max extension of the centre column. NO extra load. On top a plastic 2½-way-head (meaning the 3rd way only works in one direction, by means of a hinge) that was butchered from a no-name cheapo aluminum tripod. To attach its integrated head to the Gitzo, the upper part of the alu tripod centre column was cut off, and an aluminum 3/8" socket welded to the base of the cut-off part. Weight of this part of the construction ca 100 grams.
On top a Markins QR clamp, weight about 80 grams, connected by means of the QR plate/clamp of the cheapo tripod. To make the plate fit tightly in the clamp, I had to cover the engaging part of the former with some Tesa® tape (sic!).
The connection between the head and the Gitzo by means of the welded socket is slightly angled, so I have to use the 2½-way hinge to level the camera (when the tripod is level, as in my living room). The angle is shown exaggerated in the photo of the rig. So the camera is supported only through this hinge, not resting on the tripod head base.
Now - can you see a difference between the 2 test shots?
I have taken 3 shots of either configuration, and all 6 look the same.
I tried to measure the central diffuse grey in the target on my screen (96 dpi) with a ruler and arrived at 17 mm for all of them.
This is in my living room. Wind is another matter...
Add-on:
The camera was mounted to the Arca Swiss (type) dovetail clamps by an RRS L-bracket. This was mounted to the camera so that the left one of the small 'stirrups', which are intended to hold the camera neck strap, is squeezed tightly between the bracket and the camera body.