How much direct sun (this time of year) can these terrestrial orchid plants handle?

Sorry Ken, I have never tested the light-limits on mine, I usually treat it as one would keep a Phal. But I have moved them into brighter light without ill effects, just not into full blast sun under the glass ceiling.
Now Ludisia discolor is another story!! Full blast sun one Summer outside and the plant was completely "reborn" by late Summer. That year that basket looked so miserable, I was about to pitch it, but didn't have the heart to do it. Instead, I dropped the basket into a corner in they yard.....

Thanks, Ursula. I only have the Vanilla Orchid and the sceptrodes plants. My only shading is the solar blanket material over/around my greenhouses, and that is not really shading, just diffusing the light some.