Since I was asked, here is a sample of one of the proof sheets I've been making using XnView. The original is 3075×2175 pixels, for printing at 300dpi. This is enough to see detail on the page. For a 100% detail showing the level of detail that's visible, just click-through on the image at right.
Some of the surprising things in the exhibit (which may be in the expensive companion book) are a few of Arbus's proof sheets. Some are about what you might expect: a suite of similar shots from which just one was selected. But for most of the others, what's astonishing is their variety proofs where each photo is markedly different, of a completely different person, sometimes in another location. The photos that were printed weren't one from a set they were just the one photo.
I know that Arbus was constantly dismissive of her ability to know what was in the photo until she saw it. But the proof sheets tell a different story. In, nail it, and go on to the next thing. Pretty impressive. Scary, even.