Robert Juliat has a fixture that can change lenses to either plano-convex, pebble-convex or Fresnel. Has anyone used this instrument before? The lens option seems like a really cool idea. Just as the S4 has lense barrels, why can 't there be a uniform body and different lense options for other types of instruments. Also, I believe this makes R-J one of the few, if not the only, manufacturer to still offer a true plano-convex spot. How does this spot compare to the old style PC's. Where the problems seen in those fixtures overcome, or do these fixtures too share that grainy, hard beam?