Pochade = a free, bold, rapid sketch.
Esquisse = slightly more precise sketch than the pochade.
Étude = highly detailed, extremely precise study of specific details.
Fini (or finis, finish) = the completed, fully realized mirror-smooth painting built out of combining imagery and information from a wide variety of pochade, esquisse, études.
There's many other kinds of ways of sketching and studying - certain types of color sketching related to composition, the compositional line drawing, etc.
Many Impressionists thought of their pleine aire paintings as a kind of pochade. Monet is known to have called many of his paintings "bad pochade." Re: Emile Zola and Cézanne: here's what Zola, the champion of realism, the anti-establishmentarian himself, said about this basic topic: "I prefer a thousand times a pochade, an esquisse in the open countryside, painted by [Corot] in the open countryside, face to face with powerful reality."
Zola, Thore and others did feel that the various sketches were more potent, more realistic, and more interesting to look at than the finished paintings, valuing spontaneity over the more analytic types of creativity that go into creating the finish. Keep in mind that Poussin's and Claude's rules for painting and changing what nature looked like had by the 1850's become a series of watered-down formulae used by countless bad painters to make chintzy, sugary paintings (sort of the equivalent of today's Kinkades, or other mass-illustrators), and as such, classical and neoclassical methods were beginning to be seen as rulebound, overly strict, and not much like what real life is like. We see the same problem in many variations of realism today - the woodenness, the lack of potent symbolism, and so on.
The more extreme version of this was the Sturm und Drang movement, championed by Delacroix, which emphasized more and more the impassioned, instinctive, spontaneous aspects of creativity and less and less the analytic, logical, well-planned variations (Ingres, David).
The Hudson River School of landscape painters routinely did intensive pochade and études out in the field, and then during the winter months used all of the studies to create the monumental, large paintings in the studio (such as Frederic Church's Heart of the Andes).
It wasn't until the 20th Century that all of these different types of studies could be considered as fine art unto themselves. When that transition happened, I think many people lost sight of the purpose of the study, and how the techniques of a study were related to the purpose -- lacking that rationale and context, many study-like artworks can seem too casual, or even flippant.
Greg Scheckler
