Nikon DG-2 eyepiece magnifier on Contax 645?

[lowep]

I gather this flip up 2x magnifier ought to fit on Contax 645. Has anybody tried it?

[lowep]

also interested to know what if any difference has the Contax F-2N eyepeice, as tough to find specs and instructions for either, or is there a better way to check the accuracy of manual focus when using legacy lenses?

[lowep]

found a Contax F-2N magnifier eyepiece :-)

BUT

as far as I can figure out the Contax F-2N eyepiece comes with either a square or round eyepiece adapter, and the bloke who has one for sale informs me that his comes with the square eyepiece adapter, which does not fit the Contax 645, right?

Probably more likelihood of stumbling across the tomb of the Lost Ark than a round eyepiece adapter for this magnifier...

So back to go