No your camera position or focal length has nothing to do with IBL. Only thing matters for IBL is the environment position and brightness.

I know you are anxious for contact shadows in this image, so here I give you the simplest possible contact shadow catcher. I'm making a much more sophisticated one, but this will do for you. Only two nodes needed.

Change your ground shader to this. In the MaxDist of the AO node, I wrote 200, but Poser changed it to 199.99. Also, my 200 is with display units in Inches. You must convert, or switch your units to Inches temporarily, before typing in 200.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)