Um, Antje, if your father wants convenience a field or view camera is not for him. I do closeup and macro (above 1:1) work with Nikons and Speed Graphics.
Until I figure out a convenient way to set up the Graphics for use with focus frames (and make the frames too), they're totally useless for moving subjects. And fairly slow to set up for subjects that hold still.
I continue to use the Graphics closeup even though they're slower-working and harder to use than the Nikons because they give better results. I don't use them to get higher magnification (larger image of the main subject) than is easy with the Nikons but to get more of the scene in the frame at the magnification I'd use with a Nikon.
Oh, yeah, I usually shoot with flash. Its essential when shooting hand-held to stop movement (even when the subject is a rock, I move), very helpful for stopping subject movement when shooting from from tripod. Wind is dangerous.
In MF, this limits you to using lenses with leaf shutters. No MF camera's focal plane shutter syncs with flash at a usefully high shutter speed. Do the thought experiment (ISO 100 film, 1/30 shutter speed, broad daylight) and you'll see why.