What could be causing my plane with glass shader to act like a lens?
I want normal glass, and already have tried 2 different node setups, but it still acts like a lens.
It looks like the glass object has no thickness. Without any thickness, rays are bent only once, and behave as if everything behind the plane were inside the glass, rather than behind it.
After adding a solidify modifier (or thickness via any other method), rays passing through the glass will be bent upon entering it, then bent back upon exiting it. This should result in the expected appearance:
You could change the IOR to be 1. Then the light will no longer be refracted. But I think you had that solidify Problem mentioned above.
Well it looks like the light path node going through the math nodes is distorting things. If you just use the glass shader only the problem goes away.
I know the light path node is better for setting up glass but it seems something is off. If you want to keep the same set up so it renders faster with no fire flies try dropping the IOR to something like 1.05 and see if that fixes it.