My render above was done at 15mm. With the 1.4x factor (actually it is the square root of 2, or 1.4142), that's the equivalent of a 21 mm lens on a standard full-frame SLR. Landscape photographers generally use wide angle, 20 mm to 24 mm, for pleasing grand landscape images. That's why I used that value.

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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)