Don’t Look Too Hard

Next, relax. Don’t look too hard. We mean this as sincere and literal advice. Your eye’s sharpest color vision is in the center of your field of view. This is where color-receptor neurons known as cones are most densely concentrated. However, so-called rods, the visual receptors sensitive to black, white, and shades of gray, while insensitive to color, are more sensitive than cones to low levels of light. This means you can actually better see fainter objects with your peripheral vision than with your center-field vision. Learn to look askance at the stars. This practice is sometimes called “averted vision.” Using it, you will typically see fainter stars.
Peering through a telescope for extended periods is fun, but it can also be fatiguing. Don’t squint. Don’t peer. Step away from your telescope periodically to walk around. Relax and enjoy.
You’ll enjoy your astronomy sessions more, as well as reduce fatigue, if you practice keeping both eyes open when you look through the eyepiece. If you can’t resist the urge to close one eye, buy a pirate’s eye patch from the local toy store or costume shop. Then you can keep both eyes open without distraction and even feel like a real celestial navigator. A parrot on the shoulder is optional.