That's exactly how I came to understand the effect. I was looking at a picture of a sunset I had taken and wondering why the sun looked so much smaller than when I was there. I remembered that the sun, like the moon, is roughly the size of the thumbnail when the arm is completely stretched out, so I zoomed in the image until the sun was the right angular size, and the sizes of all the objects then appeared as in real life, only observed through tunnel vision.