Analog film photography and cameras

I have a query about the Rondinex system - specifically, I have inherited a Rondinex 35U, which requires 200cc of developer compared with 290cc per film for a Paterson tank. On the few occasions I've used it, the negatives have come out looking under developed - should the strength of the developer be increased in the same ratio as the reduction in volume? I.e. the same amount of developer per film irrespective of volume of water?

What you need to keep in mind with the Rondinex is that

• it accepts little developer (200 ml)
  
• that it uses a form of rotary agitiation
  
  

Some developers and dilutions are ill-suited. Rodinal, for example, demands a min. of 5ml concentrate per film. This means that 1+50 is about as dilute as one should generally go-- with, of course, exceptions.

Continuous agitation (as the Rondinax) provides lower development times than inversion. A good starting point are the values published in the "Massive Development Chart". Since rotation speed and style have an influence on density its just a starting point-- one anyway needs to adjust to the gamma you want for the enlarger (different illumination sources demand different levels of film densitry) or scanner.