I grow my Pterostylis outside, under 50% shade in south-eastern Australia. I've never bothered to measure the light intensity in my shadehouse so it's a bit hard to equate the amount of light my orchids get to what you'd get on a windowsill in Minnesota. Generally my plants get about Cattleya-Dendrobium light. In good light, the leaves should stay fairly flat against the surface of the mix. I don't usually take photos of leaves but these Ptst concinna pretty much show you what my plants look like under this level of light.
I had this nutans in my Sarcochilus house (Paph light) when I was playing around with conditions one year. As you can see it doesn't take much of a drop in light for the leaves to start becoming etiolated. It's now back growing amongst my other terrestrials and the rosettes are flat like the concinna above.
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