Why do they need to check Non Rendable at all is my point, im pretty sure it's possible to not have it checked
The A render will trow up a warning about that Depth of Field not work if the perspective is not on, so why not change it to Final Gather/ 10 meter or something similar, and move the DOF to the bottom of the list if that is the issue.
It's a boring message and i also think New users will think, perspective what/ where ?
And "by default" i think of a New from scratch.
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