I need to render a transparent glass cylinder as a PNG. When I use a background in C4D it looks fine, but when I render it without the background the glass seems to prick up some of the gray of the default “background”. In the first screenshot you can see it with the test background in C4D, and the second is the rendered cylinder imported to Illustrator. As you can see it is somewhat transparent but with a strong blue/gray hue. I have tried increasing Ray Depth but it didn’t help.
the refractive property of the material picks up the BG, whatever is behind it, so you would need to have the ‘green bg’ in the scene but use a tag to hide it (compositing tag in standard/physical) you will then get the glass on alpha but you will see the bg through the glass, so render it on a colour that you will want in your final comp.