I imagine that Velvia 50 would probably not be the right choice for art gallery photography. Velvia 50 is not designed for use in point light where it will block shadows completely. It's latitude is very narrow, certainly nothing like the 4-5 stops of negative film, so your exposure must be spot-on. Pushing or pulling is not the answer as either will have some detriment to one of highlights or shadows. It is best exposed in diffuse light. Rating Velvia 50 at EI40 will deliver a slightly less enriched palette (but one nonetheless characteristic of this film) and marginally better shadow detail but sometimes at the expense of highlights during long exposures, so your scenes need to be chosen carefully. It is a testy film to use and you might wish to try Velvia 100F, although the palette of that film is far removed from the gold standard set by RVP 50.