I think this is where you are having difficulty understanding the Rm3d. There is no focusing on GG with the Arca. You can compose with GG (or not), but focusing is done with distance measurement with (or without) the E-module.
Hyperfocal distance may be meaningful for cameras that do not have any front tilt or swing, which is not the case with the RM3d.
Hm.
Alpa:
Shim adjustment of back, together with all other components lends to perfect zone focus and hyperfocal distance focus. Also to viewing and perfect focus using GG. Alpa helical focus sufficient for these.
Using laser distometer one can also set the focus point rather exact using the helical focus.
Correct?
Arca:
No shim adjustment, apply fudge factors, assumes sensor is perfect parallel to camera system (including to shift, rise, lenses and GG).
GG for viewing only (unless perhaps apply same fudge factor as applied to lens focus, at a refocus post GG focus).
Focus tables require a lookup for more or less each shot.
E-module will give accurate the focus and DOF that lens is current set to, but the ultrasound is not at all times reliable. Also add cost and reliability issue.
Above correct?
Very high accuracy helical focus, but is this in reality at all useful compared to Alpa except when photographing tethered?
At tilt/swing how would one accurate determine focus without shooting tethered?
Please do not get me wrong, indeed I find the RM3D and especially RM2D interesting. Not to highjack this threat, but how would Cambo RS compare?
How about the sliding mechanisms of Arca and Cambo, are they as precise (in sliding plane) as are Alpa’s roller bearings?
Thanks!