I woke up early today, saw the Southern Cross out the bathroom window, and was off with the red light and binos to the little clearing by the house where I left a confy chair last night. I spent practically the entire session looking at one of the finest binocular fields in the sky, taking in the whole Carina Nebula and the bright open clusters NGC 3293 and 3532.
Although my retina had not seen a white photon since I went to bed last night, and although I was very careful with my dim red flashlight, and even kept one eye closed while scanning for snakes, it was about fifteen minutes before I really started to see detail. Both clusters were well resolved, and Eta Carina was bright red. The nebula extended well beyond the two central patches that barely fit into the widest telescope field. Four huge lobes around this turned it into a galactic flower, with arches of nebulosity reaching all the way out to the open clusters. To the east, near the edge of the field, a large and richly textured dark nebula, the beginning of the Great Rift. I have yet to see Barnard's Loop, but this must be comparable, although much brighter - easily seen with no filters, just 10x42s and a dark sky.
I found a comfortable crouch and lost myself in the scene, but after a while, the view deteriorated. An annoying glow was fading out the fainter emission detail and washing out the contrasting textures in the dark nebula. Soon I could not find things that I had just been observing with direct vision. I figured it was about 4:30 AM - well before first light. What the hell? I dropped the binos, and sure enough, there it was - Venus rising to the ESE, wrecking the dark sky like a distant Wal-Mart. End of session.
When I was teaching myself amateur astronomy, all the online sources, including CN, seemed to agree that it takes 15-30 minutes to dark adapt, with night vision "improving marginally for up to an hour". They also seem to suggest that brief exposure to weak light is OK, especially if it is red. Not so! Amateurs will be well served to know that deep dark adaptation takes well over an hour, and that any bright source of photons - even a red-mode Stellarium or Venus - will degrade it significantly.