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I have a project on 2048 x 1152 pixels

now I have a zoom in from a 12 field to a 6 field.

Does this mean I have to set up my shot on the double amount of pixels to end up in the right resolution, or does the camera in TVP upgrade the pixels while zooming in (so the resolution is defined by the camera)?
Does this work the same in the standard camera as in the FX multiplane camera?

Does this mean I have to set up my shot on the double amount of pixels to end up in the right resolution

Exactly. Software can interpolate between existing pixels, but no software can invent new information or guess what you want to show.