Walking on two legs isn't natural either. But many of us do it.
Seeing an "upside-down" image as natural is very natural! In fact, that is how our brain receives the image in the first place. The basic law of optics dictates that the image thrown upon our retina by the lens of our eye must be upside down and backwards...yet we perceive it as right-side up and non-reversed. So this is an exercise our brains are quite familiar with.
It is easy, at least for me -- I did not have to work hard at all to find the upside down and backwards image to be comfortable and natural way to view the scene in front of me on the GG.
What I still have problems with are camera, like Med-Format, that are right side up, but backwards.
This still drives me crazy.
Give me, both, ( Upside Down & Backwards ), or neither, ( normal viewing ).
Not Right side Up , but still Backwards.
Yes, that's the way our optical sensory system works. But it sure as hell doesn't mean that viewing a scene upside down is "natural"; the view is 180 degrees out of whack, unless one is standing on their head.
Oh, well. People like to rationalize all kinds of stuff. Who am I to stand in their way?
I just hang my pictures upside down and then they look fine :D
Seriously though...I don't notice it's uside down...and not even wrong way round (left and right)....I think we don't give our brains enough credit..
A similar thing happens if you watch TV whilst lying on the sofa. Although the TV image is actually rotated 90 degrees to your eye, your brain does the post processing and you think you are viewing it the right way round.
Well David, if you wish to be closed-minded about it, that is your choice. But I have observed otherwise. If you wish, try this experiment. Spend an hour or two on your back with your head hanging back so that the world is viewed upside down..perhaps watch TV as Steve suggests. In an hour, observe how the world seems to be orientated. Then close your eyes, sit up and see if the world looks oriented "normally" immediately after opening your eyes.
This is actually how I experienced this the first time...before I ever used a view camera. I was floating on my back on a Texas lake back in the early 70's. Of course, the above experiment might fail...your mind might be too inflexible.