Andrea: Ball heads exist which can handle large loads. The Arca Swiss B1G (giant) is rated to hold loads up to 200 lbs. The regular B1 is rated to 90 lbs. Both are traditional ball head designs. I'd guess that some of the Foba and Linhof ball heads are also pretty good in this regard. I agree with your viewpoint that using a ball head in the studio would be pretty difficult.
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