Seeing this stuff is the first time I’ve ever heard of Hume walking off ROTJ let alone Marquand actually being replaced. There have always been rumors akin to Poltergeist of George being so over the shoulder but this is really something else.

I’ve always thought ROTJ had at least some parts that didn’t quite fit with Hume’s slight lean toward softness that you see in his Bonds compared with Alec Mills sharper look I prefer in his Bonds that immediately followed. Both are great cameramen and I do think you see both’s work in ROTJ since Mills was Hume’s operator for years.

https://filmschoolrejects.com/star-wars-cinematography-history-663563e9b58d/
This article indicates that this did happen. I wonder what exactly the sources are. The production sounds a bit too business minded for sure and I had that notion really underlined when I read the making of paperback written by the producer.

As for the original post, Panavision was also the premiere rental house and would sometimes just be credited because they supplied equipment. Camera types and brands are usually chosen by the DP as each has specific strengths and weaknesses. Back in the day most films were shot with a variety of cameras from different brands.

ROTJ has less intricate lighting for sure and you can tell there was less time spent on it especially in Imperial set interiors. The film stock is improved but it never has the wow factor of SW or ESB despite being made by a team of two of the best British cameramen then working. I’d chalk it up to production interference and a lack of desire to be artistic like ESB because George hated spending all the time and money on that film when they could just do it fast.