So I assume that there is no way of automating the individual focus points in the stack with these cameras, right? Meaning you used live view and manually set focus for each of the shots? Was that a difficult process, and do you think it could be achieved in the field shooting landscapes?
I'm renting one of these devils for a few days next month. Too expensive for me to just take the plunge without knowing if it's something I could use for sellable work, in a practical sense.
Yes, manually set. At any given aperture and distance-to-subject, a little practice makes it fairly easy & repeatable. Even easier for landscape distances and takes fewer frames at optimum aperture (for sharpness) for good front to back depth. I use a Hoodman loupe sometimes when I need to see my points more precisely. For this image, a couple of practice runs got me dialed in. I hate fly-by-wire manual focus in general, but the the sound produced by the Sigma's focusing actually helps me be more precise - go figure!
I think you'll easily get the feel for it. I'd reccomend testing at home for landscape distances at you preferred aperture. Being able to check stack quality immediately will go a long way toward getting a routine that will be dependable in the field.
Let me add that the Foveon sensor is very sensitive to under exposure. So when your rental arrives make your first tests be to dial in an appropriate ex-comp setting. E.g. w/ my DP2 I start at +.7, and w/ the DP3 it is +.3.
Under exposure will produce an inordinate increase in shadow noise, and when severe, ugly and uncorrectable banding. These cameras have stunning image quality, but within very limited parameters. I truly love mine and would probably give up my other gear before I did the Merrills. Addictive.