Back to the filter question, always remember that filters don't
lighten their own color, they hold back (thinner on the neg,
darker on the print) other colors, holding back their opposite
(or complementary) colors the most. Objects of their own color
remain relatively unaffected. It's the application of the filter
factor, increasing exposure, that make it's own color objects
heavier on the negative, or lighter on the print, depending on
how you decide to print. It makes sense to me that the orange
worked well for Marcio, as it has some yellow, related to green,
so, not too extreme, but enough to enhance the value differences
within the green leaves.