Before driving home from Lake Sonoma last night we took a look at the naked-eye cluster NGC 2244, situated in the heart of the Rosette nebula. The cluster, itself, has an integrated V magnitude of 4.8 including a number of mag 6-7 stars and is a fairly easy naked-eye sighting in dark skies (along with NGC 2264 = "Christmas Tree" cluster to the north). The naked-eye "clump" of stars is not the Rosette, though, which is an HII wreath surrounding the cluster and is over a degree in diameter.
I generally find using nebula filters naked-eye inconvenient, but as an experiment I grabbed a 2" OIII filter and was surprised to see the diameter of the hazy glow nearly doubled in size (pulling in the faint nebulosity of the Rosette). At the same time, the overall surface brightness decreased because of the diminished stars. Can others verify this result?