Paired numeric values on the Model Sampling Flux node. Max Shift is the primary value swept when exploring the node's effect; Base Shift is typically held constant as a baseline (e.g. 0.5) while Max Shift varies. Changing them alters fine detail and can shift overall composition, while color palette and broad composition tend to stay consistent.
Demonstrated fixes: correcting a fish's shape, seating a tail correctly behind clothing instead of clipping through it, and making a facial expression read as more 'sinister' — all without changing seed or prompt.
The usable range between Max Shift and Base Shift narrows as the node's Width/Height setting increases — e.g. at 2048x2048 there's much less headroom before output quality degrades than at 1024x1024. Values can also be inverted (Max Shift lower than Base Shift) for different, sometimes useful, results.
Hold Base Shift constant (e.g. 0.5) and sweep Max Shift across a range (e.g. 0.75–1.75) to find a value that fixes an unwanted detail without discarding the overall composition. Prefer a lower node resolution (around 1024x1024) for a wider usable range to experiment within.