Have you ever noticed that the longer you stare directly at something in the dark, the fuzzier and more out-of-focus it gets? But, the moment you shift your focus just to the side of the item, you are able to see a clearer image, right? Focusing directly on something calls upon light-gathering cones in your retina; cones are more centered in the retina and as such provide crisp focus in good light. A little trick for seeing owl silhouettes better at night: try shifting your focus just to the side of the bird, and by doing so, you begin to rely upon the more scattered placement of the rods in your retina, which are much better at processing images in dim light.
This can be done while looking through your binoculars, or even your scope. Other birders will soon wonder if you have night-vision equipment when you start to make sense of those ear tufts on that Great Horned Owl over a km away 😉