Well...the problem with a ballhead is leveling. It's no issue as long as a (well built) tripod is standing on perfectly straight underground. As soon as it doesn't, you will run into trouble: You normally would use the ballhead to level the camera above it. And then leave it and use the ballhead's rotor with the degree markings. However: While the camera is leveled (for the moment) the turn axis of the ballhead's rotor isn't, since it sits underneath the ball that does the leveling. Of course you could try to adjust the lenghts of the tripod legs to level the rotor. But that would be very complicated and almost impossible to achieve (if you want accuracy). So the best option would be to use the ballhead (or preferably a leveling base, since more accurate) to level an indexing rotor. One other option would be to use the ballhead upside down. Sounds insane, but there are adapters to achieve that. But then you have to “retrofit“ your ballhead every time...
I just ordered this panorama head:
mantona Panorama Head 360°, walimex & walimex pro by Mediaresort
I wanted something as compact, lightweight and uncomplicated as possible. It is good enough for my DP2M, since it got an 15° indexing (including ratchets). 18° would be perfect for 30mm @ APS-C but 15 are close enough for me. More overlapping isn't bad anyway.
It however won't do for the DP3M...(11°).
Btw...This table might be helpful:
Tabellen, Daten und Infos fr Panoramafotografen
It's in German but it should be self explanatory. The first value in the table (at the bottom of the site) is the number of steps/photos for a 360° pano, the second the degrees for each step.
Since I mentioned “compact, lightweight and uncomplicated“ above...I got a nice (and expensive) setup for multirow panos. Manfrotto 303 SPH, including a manfrotto leveling base. But it is too bulky and heavy (5kg, including the tripod, but not the camera)...
https://www.dropbox.com/s/cx2i7rmo1wqq8ip/Pano.jpg
:facesmack: 